diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,23 @@
+## 1.4.1.0
+
+### Added
+
+- Support for switching vertical wheel scrolling to horizontal in scroll widget by pressing the shift key ([PR #137](https://github.com/fjvallarino/monomer/pull/137)).
+- Drawing and theme utility functions ([PR #138](https://github.com/fjvallarino/monomer/pull/138)).
+- `boxFilterEvent` config option, exposing Container's filterEvent functionality ([PR #146](https://github.com/fjvallarino/monomer/pull/146)).
+- `pointToLineDistance` utility function ([PR #150](https://github.com/fjvallarino/monomer/pull/150)).
+
+### Fixed
+
+- Bug where memory based image widget would not render their new state after a merge ([PR #147](https://github.com/fjvallarino/monomer/pull/147)). Thanks @CamdenKuwahara!
+- Fix memory leak in NanoVGRenderer's image initialization. Dispose unused images in image widget ([PR #149](https://github.com/fjvallarino/monomer/pull/149)).
+
+### Changed
+
+- Restricts toggleButton's type argument for configuration options to Bool (the only valid type) ([PR #150](https://github.com/fjvallarino/monomer/pull/150)).
+- Avoids drawing borders if width == 0 ([PR #150](https://github.com/fjvallarino/monomer/pull/150)).
+- Updates default style for tooltip widget ([PR #150](https://github.com/fjvallarino/monomer/pull/150)).
+
 ## 1.4.0.0
 
 ### Breaking changes
diff --git a/monomer.cabal b/monomer.cabal
--- a/monomer.cabal
+++ b/monomer.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           monomer
-version:        1.4.0.0
+version:        1.4.1.0
 synopsis:       A GUI library for writing native Haskell applications.
 description:    Monomer is an easy to use, cross platform, GUI library for writing native
                 Haskell applications.
diff --git a/src/Monomer/Common/BasicTypes.hs b/src/Monomer/Common/BasicTypes.hs
--- a/src/Monomer/Common/BasicTypes.hs
+++ b/src/Monomer/Common/BasicTypes.hs
@@ -101,6 +101,18 @@
 negPoint :: Point -> Point
 negPoint (Point x y) = Point (-x) (-y)
 
+{-|
+Returns the minimum distance from the point given as first argument to the line
+formed by the points given as second and third arguments.
+-}
+pointToLineDistance :: Point -> Point -> Point -> Double
+pointToLineDistance p0 p1 p2 = distNum / distDen where
+  Point px0 py0 = p0
+  Point px1 py1 = p1
+  Point px2 py2 = p2
+  distNum = abs ((px2 - px1) * (py1 - py0) - (px1 - px0) * (py2 - py1))
+  distDen = sqrt ((px2 - px1) ** 2 + (py2 - py1) ** 2)
+
 -- | Checks if a coordinate is inside the horizontal range of a rect.
 coordInRectH :: Double -> Rect -> Bool
 coordInRectH px (Rect x y w h) = px >= x && px < x + w
diff --git a/src/Monomer/Core/ThemeTypes.hs b/src/Monomer/Core/ThemeTypes.hs
--- a/src/Monomer/Core/ThemeTypes.hs
+++ b/src/Monomer/Core/ThemeTypes.hs
@@ -9,7 +9,7 @@
 Theme configuration types.
 -}
 {-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE Strict #-}
+{-# LANGUAGE StrictData #-}
 
 module Monomer.Core.ThemeTypes where
 
@@ -19,7 +19,6 @@
 
 import qualified Data.Map.Strict as M
 
-import Monomer.Common
 import Monomer.Core.StyleTypes
 import Monomer.Graphics.ColorTable
 import Monomer.Graphics.Types
diff --git a/src/Monomer/Core/Themes/BaseTheme.hs b/src/Monomer/Core/Themes/BaseTheme.hs
--- a/src/Monomer/Core/Themes/BaseTheme.hs
+++ b/src/Monomer/Core/Themes/BaseTheme.hs
@@ -215,7 +215,8 @@
   & L.text . non def . L.fontColor ?~ tooltipText themeMod
   & L.bgColor ?~ tooltipBg themeMod
   & L.border ?~ border 1 (tooltipBorder themeMod)
-  & L.padding ?~ padding 4
+  & L.padding ?~ padding 6
+  & L.radius ?~ radius 4
 
 baseBasic :: BaseThemeColors -> ThemeState
 baseBasic themeMod = def
diff --git a/src/Monomer/Core/Themes/SampleThemes.hs b/src/Monomer/Core/Themes/SampleThemes.hs
--- a/src/Monomer/Core/Themes/SampleThemes.hs
+++ b/src/Monomer/Core/Themes/SampleThemes.hs
@@ -117,8 +117,8 @@
   slSelectedText = black,
   slSelectedFocusBorder = blue07,
 
-  tooltipBorder = gray09,
-  tooltipBg = gray10,
+  tooltipBorder = gray08,
+  tooltipBg = gray07,
   tooltipText = black
 }
 
@@ -216,8 +216,8 @@
   slSelectedText = white,
   slSelectedFocusBorder = blue08,
 
-  tooltipBorder = gray09,
-  tooltipBg = gray04,
+  tooltipBorder = gray05,
+  tooltipBg = rgbHex "#1D212B",
   tooltipText = white
 }
 
diff --git a/src/Monomer/Core/Util.hs b/src/Monomer/Core/Util.hs
--- a/src/Monomer/Core/Util.hs
+++ b/src/Monomer/Core/Util.hs
@@ -31,19 +31,19 @@
 import qualified Monomer.Core.Lens as L
 
 -- | Returns the 'Path' associated to a given 'WidgetKey', if any. The search is
---   restricted to the parent _Composite_.
+--   restricted to the parent "Monomer.Widgets.Composite".
 pathFromKey :: WidgetEnv s e -> WidgetKey -> Maybe Path
 pathFromKey wenv key = fmap (^. L.info . L.path) node where
   node = Map.lookup key (wenv ^. L.widgetKeyMap)
 
 -- | Returns the 'WidgetId' associated to a given 'WidgetKey', if any. The
---   search is restricted to the parent _Composite_.
+--   search is restricted to the parent "Monomer.Widgets.Composite".
 widgetIdFromKey :: WidgetEnv s e -> WidgetKey -> Maybe WidgetId
 widgetIdFromKey wenv key = fmap (^. L.info . L.widgetId) node where
   node = Map.lookup key (wenv ^. L.widgetKeyMap)
 
 -- | Returns the 'WidgetNodeInfo' associated to the given 'WidgetKey', if any.
---   The search is restricted to the parent _Composite_.
+--   The search is restricted to the parent "Monomer.Widgets.Composite".
 nodeInfoFromKey :: WidgetEnv s e -> WidgetKey -> Maybe WidgetNodeInfo
 nodeInfoFromKey wenv key = path >>= nodeInfoFromPath wenv where
   path = pathFromKey wenv key
diff --git a/src/Monomer/Core/WidgetTypes.hs b/src/Monomer/Core/WidgetTypes.hs
--- a/src/Monomer/Core/WidgetTypes.hs
+++ b/src/Monomer/Core/WidgetTypes.hs
@@ -68,7 +68,7 @@
   | FocusBwd  -- ^ Focus moving backward (usually right to left, top to bottom).
   deriving (Eq, Show)
 
--- | "WidgetRequest" specific for window related operations.
+-- | 'WidgetRequest' specific for window related operations.
 data WindowRequest
   = WindowSetTitle Text  -- ^ Sets the title of the window to the given text.
   | WindowSetFullScreen  -- ^ Switches to fullscreen mode.
@@ -216,9 +216,12 @@
   -- | Requests to exit the application. Can also be used to cancel a previous
   --   request (or a window close).
   | ExitApplication Bool
-  -- | Performs a "WindowRequest".
+  -- | Performs a 'WindowRequest'.
   | UpdateWindow WindowRequest
-  -- | Request a model update. This usually involves lenses and "widgetDataSet".
+  {-|
+  Request a model update. This usually involves lenses and
+  'Monomer.Widgets.Util.Widget.widgetDataSet'.
+  -}
   | UpdateModel (s -> s)
   -- | Updates the path of a given widget. Both "Monomer.Widgets.Single" and
   --   "Monomer.Widgets.Container" handle this automatically.
@@ -273,11 +276,13 @@
 
 {-|
 Result of widget operations (init, merge, handleEvent, etc). The node is
-mandatory. The "resultNode", "resultEvts", "resultReqs" and "resultReqsEvts"
-helper functions can also be used.
+mandatory. The 'Monomer.Widgets.Util.Widget.resultNode',
+'Monomer.Widgets.Util.Widget.resultEvts',
+'Monomer.Widgets.Util.Widget.resultReqs' and
+'Monomer.Widgets.Util.Widget.resultReqsEvts' helper functions can also be used.
 
 In general a result starts in a child widget, but parent widgets can append
-requets or new versions of themselves.
+requests or new versions of themselves.
 -}
 data WidgetResult s e = WidgetResult {
   _wrNode :: WidgetNode s e,              -- ^ The updated widget node.
@@ -322,10 +327,12 @@
   _weWindowSize :: Size,
   -- | The active map of shared data.
   _weWidgetShared :: MVar (Map Text WidgetShared),
-  {-
+  {-|
   The active map of WidgetKey -> WidgetNode, if any. This map is restricted to
-  to the parent 'Composite'. Do not use this map directly, rely instead on the
-  'widgetIdFromKey', 'nodeInfoFromKey' and 'nodeInfoFromPath' utility functions.
+  to the parent "Monomer.Widgets.Composite". Do not use this map directly, rely
+  instead on the 'Monomer.Core.Util.widgetIdFromKey',
+  'Monomer.Core.Util.nodeInfoFromKey' and 'Monomer.Core.Util.nodeInfoFromPath'
+  utility functions.
   -}
   _weWidgetKeyMap :: WidgetKeyMap s e,
   -- | The currently hovered path, if any.
@@ -625,8 +632,8 @@
     Receives a message and, optionally, returns a result. This can include an
     updated version of the widget (in case it has internal state), user events
     or requests to the runtime. There is no validation regarding the message
-    type, and the widget should take care of _casting_ to the correct type using
-    "Data.Typeable.cast"
+    type, and the widget should take care of /casting/ to the correct type using
+    'Data.Typeable.cast'.
 
     Arguments:
 
diff --git a/src/Monomer/Graphics/NanoVGRenderer.hs b/src/Monomer/Graphics/NanoVGRenderer.hs
--- a/src/Monomer/Graphics/NanoVGRenderer.hs
+++ b/src/Monomer/Graphics/NanoVGRenderer.hs
@@ -471,7 +471,7 @@
 
 imgInsertNew :: Text -> ImageDef -> ImagesMap -> VG.Image -> ImagesMap
 imgInsertNew name imageDef imagesMap nvImg = newImagesMap where
-  image = Image imageDef nvImg 0
+  image = Image imageDef nvImg 1
   newImagesMap = M.insert name image imagesMap
 
 imgDelete :: Text -> ImagesMap -> ImagesMap
diff --git a/src/Monomer/Widgets/Composite.hs b/src/Monomer/Widgets/Composite.hs
--- a/src/Monomer/Widgets/Composite.hs
+++ b/src/Monomer/Widgets/Composite.hs
@@ -170,14 +170,14 @@
   = Model s
   -- | Raises a new event, which will be handled in the same cycle.
   | Event e
-  -- | Raises an event that will be handled by the parent.
+  -- | Raises an event that will be handled by the parent Composite.
   | Report ep
   -- | Generates a 'WidgetRequest'.
   | Request (WidgetRequest s e)
   {-|
-  Generates a 'WidgetRequest' matching the parent's types. Useful when receiving
-  requests as configuration from the parent, since the types will not match
-  otherwise.
+  Generates a 'WidgetRequest' matching the parent Composite's type. Useful when
+  receiving requests as configuration from the parent, since the types will not
+  match otherwise.
   -}
   | RequestParent (WidgetRequest sp ep)
   {-|
diff --git a/src/Monomer/Widgets/Container.hs b/src/Monomer/Widgets/Container.hs
--- a/src/Monomer/Widgets/Container.hs
+++ b/src/Monomer/Widgets/Container.hs
@@ -258,7 +258,7 @@
 
 {-|
 Receives a System event and, optionally, modifies the event, its target, or
-cancels the event propagation by returning null.
+stops the event propagation by returning Nothing.
 
 Examples can be found in "Monomer.Widgets.Containers.Base.LabeledItem".
 -}
diff --git a/src/Monomer/Widgets/Containers/Box.hs b/src/Monomer/Widgets/Containers/Box.hs
--- a/src/Monomer/Widgets/Containers/Box.hs
+++ b/src/Monomer/Widgets/Containers/Box.hs
@@ -58,7 +58,8 @@
   -- * Constructors
   box,
   box_,
-  expandContent
+  expandContent,
+  boxFilterEvent
 ) where
 
 import Control.Applicative ((<|>))
@@ -101,11 +102,13 @@
 - 'onClickEmptyReq': generates a WidgetRequest on click in empty area.
 - 'expandContent': if the inner widget should use all the available space. To be
   able to use alignment options, this must be False (the default).
+- 'boxFilterEvent': allows filtering or modifying a 'SystemEvent'.
 -}
 data BoxCfg s e = BoxCfg {
   _boxExpandContent :: Maybe Bool,
   _boxIgnoreEmptyArea :: Maybe Bool,
   _boxSizeReqUpdater :: [SizeReqUpdater],
+  _boxFilterEvent :: Maybe (ContainerFilterHandler s e),
   _boxMergeRequired :: Maybe (WidgetEnv s e -> s -> s -> Bool),
   _boxAlignH :: Maybe AlignH,
   _boxAlignV :: Maybe AlignV,
@@ -124,6 +127,7 @@
     _boxExpandContent = Nothing,
     _boxIgnoreEmptyArea = Nothing,
     _boxSizeReqUpdater = [],
+    _boxFilterEvent = Nothing,
     _boxMergeRequired = Nothing,
     _boxAlignH = Nothing,
     _boxAlignV = Nothing,
@@ -142,6 +146,7 @@
     _boxExpandContent = _boxExpandContent t2 <|> _boxExpandContent t1,
     _boxIgnoreEmptyArea = _boxIgnoreEmptyArea t2 <|> _boxIgnoreEmptyArea t1,
     _boxSizeReqUpdater = _boxSizeReqUpdater t1 <> _boxSizeReqUpdater t2,
+    _boxFilterEvent = _boxFilterEvent t2 <|> _boxFilterEvent t1,
     _boxMergeRequired = _boxMergeRequired t2 <|> _boxMergeRequired t1,
     _boxAlignH = _boxAlignH t2 <|> _boxAlignH t1,
     _boxAlignV = _boxAlignV t2 <|> _boxAlignV t1,
@@ -295,6 +300,15 @@
   _boxExpandContent = Just True
 }
 
+{-|
+Receives a System event and, optionally, modifies the event, its target, or
+stops the event propagation by returning Nothing.
+-}
+boxFilterEvent :: ContainerFilterHandler s e -> BoxCfg  s e
+boxFilterEvent handler = def {
+  _boxFilterEvent = Just handler
+}
+
 newtype BoxState s = BoxState {
   _bxsModel :: Maybe s
 }
@@ -330,6 +344,7 @@
     containerInit = init,
     containerMergeChildrenReq = mergeRequired,
     containerMerge = merge,
+    containerFilterEvent = filterEvent,
     containerHandleEvent = handleEvent,
     containerGetSizeReq = getSizeReq,
     containerResize = resize
@@ -357,6 +372,10 @@
   getCurrentStyle = currentStyle_ currentStyleConfig where
     currentStyleConfig = def
       & L.isActive .~ isNodeTreeActive
+
+  filterEvent = case _boxFilterEvent config of
+    Just handler -> handler
+    _ -> \wenv node target evt -> Just (target, evt)
 
   handleEvent wenv node target evt = case evt of
     Focus prev -> handleFocusChange node prev (_boxOnFocusReq config)
diff --git a/src/Monomer/Widgets/Containers/Scroll.hs b/src/Monomer/Widgets/Containers/Scroll.hs
--- a/src/Monomer/Widgets/Containers/Scroll.hs
+++ b/src/Monomer/Widgets/Containers/Scroll.hs
@@ -588,8 +588,12 @@
       result
         | needsUpdate = Just $ makeResult newState
         | otherwise = Nothing
-      stepX = wheelRate * wx
-      stepY = wheelRate * wy
+      stepX
+        | shiftPressed && changedY = wheelRate * wy
+        | otherwise = wheelRate * wx
+      stepY
+        | shiftPressed = 0
+        | otherwise = wheelRate * wy
       newState = state {
         _sstDeltaX = scrollAxisH (stepX + dx),
         _sstDeltaY = scrollAxisV (stepY + dy)
@@ -601,6 +605,7 @@
       style = scrollCurrentStyle wenv node
       contentArea = getContentArea node style
       mousePos = wenv ^. L.inputStatus . L.mousePos
+      shiftPressed = isShiftPressed (wenv ^. L.inputStatus . L.keyMod)
 
       Rect cx cy cw ch = contentArea
       sctx = scrollStatus config wenv node state mousePos
diff --git a/src/Monomer/Widgets/Containers/Tooltip.hs b/src/Monomer/Widgets/Containers/Tooltip.hs
--- a/src/Monomer/Widgets/Containers/Tooltip.hs
+++ b/src/Monomer/Widgets/Containers/Tooltip.hs
@@ -11,8 +11,8 @@
 
 Tooltip styling is a bit unusual, since it is applied to the overlaid element.
 This means padding will not be shown for the contained child element, but only
-on the message when the tooltip is active. If you need padding around the child
-element, you can use a "Monomer.Widgets.Containers.Box" around it.
+on the message when the tooltip is active. If padding around the child element
+is needed, "Monomer.Widgets.Containers.Box" can be used to wrap it.
 
 @
 tooltip "Click the button" (buttom \"Accept\" AcceptAction)
diff --git a/src/Monomer/Widgets/Singles/Button.hs b/src/Monomer/Widgets/Singles/Button.hs
--- a/src/Monomer/Widgets/Singles/Button.hs
+++ b/src/Monomer/Widgets/Singles/Button.hs
@@ -59,6 +59,7 @@
 - 'ellipsis': if ellipsis should be used for overflown text.
 - 'multiline': if text may be split in multiple lines.
 - 'maxLines': maximum number of text lines to show.
+- 'ignoreTheme': whether to load default style from theme or start empty.
 - 'resizeFactor': flexibility to have more or less spaced assigned.
 - 'resizeFactorW': flexibility to have more or less horizontal spaced assigned.
 - 'resizeFactorH': flexibility to have more or less vertical spaced assigned.
@@ -184,14 +185,14 @@
 
 {-|
 Creates a button with main styling. Useful to highlight an option, such as
-"Accept", when multiple buttons are available.
+\"Accept\", when multiple buttons are available.
 -}
 mainButton :: WidgetEvent e => Text -> e -> WidgetNode s e
 mainButton caption handler = button_ caption handler [mainConfig]
 
 {-|
 Creates a button with main styling. Useful to highlight an option, such as
-"Accept", when multiple buttons are available. Accepts config.
+\"Accept\", when multiple buttons are available. Accepts config.
 -}
 mainButton_ :: WidgetEvent e => Text -> e -> [ButtonCfg s e] -> WidgetNode s e
 mainButton_ caption handler configs = button_ caption handler newConfigs where
@@ -199,7 +200,7 @@
 
 {-|
 Creates a button with main styling. Useful to highlight an option, such as
-"Accept", when multiple buttons are available. Accepts config but does not
+\"Accept\", when multiple buttons are available. Accepts config but does not
 require an event. See 'buttonD_'.
 -}
 mainButtonD_ :: WidgetEvent e => Text -> [ButtonCfg s e] -> WidgetNode s e
@@ -220,9 +221,10 @@
 use this version, adding an 'onClick' handler in configs.
 
 Using this constructor directly can be helpful in cases where the event to be
-raised belongs in a _Composite_ above in the widget tree, outside the scope of
-the Composite that contains the button. This parent Composite can be reached by
-sending a message ('SendMessage') to its 'WidgetId' using 'onClickReq'.
+raised belongs in a "Monomer.Widgets.Composite" above in the widget tree,
+outside the scope of the Composite that contains the button. This parent
+Composite can be reached by sending a message ('SendMessage') to its 'WidgetId'
+using 'onClickReq'.
 -}
 buttonD_ :: WidgetEvent e => Text -> [ButtonCfg s e] -> WidgetNode s e
 buttonD_ caption configs = buttonNode where
diff --git a/src/Monomer/Widgets/Singles/Image.hs b/src/Monomer/Widgets/Singles/Image.hs
--- a/src/Monomer/Widgets/Singles/Image.hs
+++ b/src/Monomer/Widgets/Singles/Image.hs
@@ -48,7 +48,7 @@
 import Data.ByteString (ByteString)
 import Data.Char (toLower)
 import Data.Default
-import Data.Map (Map)
+import Data.Map.Strict (Map)
 import Data.Maybe
 import Data.List (isPrefixOf)
 import Data.Text (Text)
@@ -62,7 +62,7 @@
 import qualified Codec.Picture as Pic
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Lazy as BSL
-import qualified Data.Map as Map
+import qualified Data.Map.Strict as Map
 import qualified Data.Text as T
 import qualified Network.Wreq.Session as Sess
 
@@ -303,7 +303,7 @@
     singleRender = render
   }
 
-  !isImageMem = case imgSource of
+  isImageMem !source = case source of
     ImageMem{} -> True
     _ -> False
 
@@ -324,20 +324,30 @@
   merge wenv newNode oldNode oldState = result where
     wid = newNode ^. L.info . L.widgetId
     path = newNode ^. L.info . L.path
+
     oldSource = isImageSource oldState
-    imgPath = imgName imgSource
-    prevPath = imgName oldSource
 
+    newPath = imgName imgSource
+    oldPath = imgName oldSource
+    isNewMem = isImageMem imgSource
+    isOldMem = isImageMem oldSource
+
     sameImgNode = newNode
       & L.widget .~ makeImage imgSource config oldState
-    newMemReqs = [ RemoveRendererImage prevPath ]
-    newImgReqs = [
-        RemoveRendererImage prevPath,
-        RunTask wid path (handleImageLoad config wenv imgPath)
+
+    disposeOld = [ RunTask wid path (handleImageDispose wenv oldPath) | not isOldMem ]
+
+    newMemReqs = disposeOld ++ [
+        RemoveRendererImage oldPath,
+        ResizeWidgets wid
       ]
+    newImgReqs = disposeOld ++ [
+        RemoveRendererImage oldPath,
+        RunTask wid path (handleImageLoad config wenv newPath)
+      ]
     result
       | oldSource == imgSource = resultNode sameImgNode
-      | isImageMem = resultReqs newNode newMemReqs
+      | isNewMem = resultReqs newNode newMemReqs
       | otherwise = resultReqs newNode newImgReqs
 
   dispose wenv node = resultReqs node reqs where
@@ -458,6 +468,7 @@
   -- loading images in parallel. The main MVar is only taken until the image's
   -- MVar is retrieved/created.
   (sharedMap, sess) <- takeMVar sharedMapMVar >>= getImagesSession
+
   sharedImgMVar <- case useShared (Map.lookup key sharedMap) of
     Just mvar -> return mvar
     Nothing -> newMVar emptyImgState
@@ -465,6 +476,7 @@
 
   -- Take the image's MVar until done
   sharedImg <- takeMVar sharedImgMVar
+
   (result, newSharedImg) <- case sharedImg of
     Just (oldState, oldCount) -> do
       return (ImageLoaded oldState, Just (oldState, oldCount + 1))
@@ -488,15 +500,18 @@
 handleImageDispose :: WidgetEnv s e -> Text -> IO ()
 handleImageDispose wenv path = do
   sharedMap <- takeMVar sharedMapMVar
+
   newSharedMap <- case useShared (Map.lookup key sharedMap) of
     Just mvar -> do
       sharedImg <- takeMVar mvar
+
       return $ case sharedImg of
         Just (oldState :: ImageState, oldCount :: Int)
           | oldCount > 1 ->
               sharedMap & at key ?~ WidgetShared (oldState, oldCount - 1)
         _ -> sharedMap & at key .~ Nothing
     Nothing -> return sharedMap
+
   putMVar sharedMapMVar newSharedMap
   where
     sharedMapMVar = wenv ^. L.widgetShared
diff --git a/src/Monomer/Widgets/Singles/Label.hs b/src/Monomer/Widgets/Singles/Label.hs
--- a/src/Monomer/Widgets/Singles/Label.hs
+++ b/src/Monomer/Widgets/Singles/Label.hs
@@ -17,7 +17,7 @@
 Multi-line label:
 
 @
-label_ "This is a\nmultiline label" [multiline]
+label_ "This is a\\nmultiline label" [multiline]
 @
 -}
 {-# LANGUAGE DeriveGeneric #-}
diff --git a/src/Monomer/Widgets/Singles/ToggleButton.hs b/src/Monomer/Widgets/Singles/ToggleButton.hs
--- a/src/Monomer/Widgets/Singles/ToggleButton.hs
+++ b/src/Monomer/Widgets/Singles/ToggleButton.hs
@@ -67,10 +67,10 @@
 - 'onChange': event to raise when the value changes.
 - 'onChangeReq': 'WidgetRequest' to generate when the value changes.
 -}
-type ToggleButtonCfg = OptionButtonCfg
+type ToggleButtonCfg s e = OptionButtonCfg s e Bool
 
 -- | Sets the style for the Off state of the toggle button.
-toggleButtonOffStyle :: Style -> ToggleButtonCfg s e a
+toggleButtonOffStyle :: Style -> ToggleButtonCfg s e
 toggleButtonOffStyle = optionButtonOffStyle
 
 -- | Creates a toggleButton using the given lens.
@@ -84,7 +84,7 @@
 toggleButton_
   :: Text
   -> ALens' s Bool
-  -> [ToggleButtonCfg s e Bool]
+  -> [ToggleButtonCfg s e]
   -> WidgetNode s e
 toggleButton_ caption field cfgs = newNode where
   newNode = toggleButtonD_ caption (WidgetLens field) cfgs
@@ -106,7 +106,7 @@
   => Text
   -> Bool
   -> (Bool -> e)
-  -> [ToggleButtonCfg s e Bool]
+  -> [ToggleButtonCfg s e]
   -> WidgetNode s e
 toggleButtonV_ caption value handler configs = newNode where
   widgetData = WidgetValue value
@@ -117,7 +117,7 @@
 toggleButtonD_
   :: Text
   -> WidgetData s Bool
-  -> [ToggleButtonCfg s e Bool]
+  -> [ToggleButtonCfg s e]
   -> WidgetNode s e
 toggleButtonD_ caption widgetData configs = toggleButtonNode where
   config = mconcat configs
diff --git a/src/Monomer/Widgets/Util/Drawing.hs b/src/Monomer/Widgets/Util/Drawing.hs
--- a/src/Monomer/Widgets/Util/Drawing.hs
+++ b/src/Monomer/Widgets/Util/Drawing.hs
@@ -22,6 +22,8 @@
   drawLine,
   drawRect,
   drawRectBorder,
+  drawTriangle,
+  drawTriangleBorder,
   drawArc,
   drawArcBorder,
   drawEllipse,
@@ -205,6 +207,49 @@
 drawRectBorder renderer rect border (Just radius) =
   drawRoundedRectBorder renderer rect border radius
 
+{-|
+Draws a filled triangle with the given color.
+
+The points should be provided in clockwise order.
+-}
+drawTriangle
+  :: Renderer     -- ^ The renderer.
+  -> Point        -- ^ The first point.
+  -> Point        -- ^ The second point.
+  -> Point        -- ^ The third point.
+  -> Maybe Color  -- ^ The color. If Nothing, the triangle will not be drawn.
+  -> IO ()        -- ^ The resulting action.
+drawTriangle _ _ _ _ Nothing = return ()
+drawTriangle renderer p1 p2 p3 (Just color) = do
+  beginPath renderer
+  setFillColor renderer color
+  moveTo renderer p1
+  renderLineTo renderer p2
+  renderLineTo renderer p3
+  closePath renderer
+  fill renderer
+
+-- | Draws a triangle's border with the given color and width.
+drawTriangleBorder
+  :: Renderer     -- ^ The renderer.
+  -> Point        -- ^ The first point.
+  -> Point        -- ^ The second point.
+  -> Point        -- ^ The third point.
+  -> Double       -- ^ The border width.
+  -> Maybe Color  -- ^ The color. If Nothing, the triangle will not be drawn.
+  -> IO ()        -- ^ The resulting action.
+drawTriangleBorder _ _ _ _ _ Nothing = return ()
+drawTriangleBorder renderer p1 p2 p3 width (Just color) =
+  when (width > 0) $ do
+    beginPath renderer
+    setStrokeColor renderer color
+    setStrokeWidth renderer width
+    moveTo renderer p1
+    renderLineTo renderer p2
+    renderLineTo renderer p3
+    closePath renderer
+    stroke renderer
+
 -- | Draws a filled arc, delimited by a rect and within the given angles.
 drawArc
   :: Renderer      -- ^ The renderer.
@@ -236,12 +281,13 @@
   -> Double        -- ^ The arc width.
   -> IO ()         -- ^ The resulting action.
 drawArcBorder renderer rect start end winding Nothing width = return ()
-drawArcBorder renderer rect start end winding (Just color) width = do
-  beginPath renderer
-  setStrokeColor renderer color
-  setStrokeWidth renderer width
-  renderArc renderer center radius start end winding
-  stroke renderer
+drawArcBorder renderer rect start end winding (Just color) width =
+  when (width > 0) $ do
+    beginPath renderer
+    setStrokeColor renderer color
+    setStrokeWidth renderer width
+    renderArc renderer center radius start end winding
+    stroke renderer
   where
     Rect rx ry rw rh = rect
     radius = min ((rw - width) / 2) ((rh - width) / 2)
@@ -269,12 +315,13 @@
   -> IO ()         -- ^ The resulting action.
 drawEllipseBorder renderer rect Nothing _ = return ()
 drawEllipseBorder renderer rect (Just color) width =
-  forM_ contentRect $ \finalRect -> do
-    beginPath renderer
-    setStrokeColor renderer color
-    setStrokeWidth renderer width
-    renderEllipse renderer finalRect
-    stroke renderer
+  when (width > 0) $
+    forM_ contentRect $ \finalRect -> do
+      beginPath renderer
+      setStrokeColor renderer color
+      setStrokeWidth renderer width
+      renderEllipse renderer finalRect
+      stroke renderer
   where
     contentRect = subtractFromRect rect w w w w
     w = width / 2
@@ -437,19 +484,21 @@
 drawRectCorner _ _ ocorner Nothing Nothing = return points where
   points = (ocorner, ocorner, ocorner)
 drawRectCorner renderer cor ocorner ms1 ms2 = do
-  beginPath renderer
+  when (w1 > 0 && w2 > 0) $ do
+    beginPath renderer
 
-  if color1 == color2
-    then setFillColor renderer color1
-    else setFillLinearGradient renderer g1 g2 color1 color2
+    if color1 == color2
+      then setFillColor renderer color1
+      else setFillLinearGradient renderer g1 g2 color1 color2
 
-  moveTo renderer o1
-  renderLineTo renderer icorner
-  renderLineTo renderer o2
-  renderLineTo renderer ocorner
-  closePath renderer
+    moveTo renderer o1
+    renderLineTo renderer icorner
+    renderLineTo renderer o2
+    renderLineTo renderer ocorner
+    closePath renderer
 
-  fill renderer
+    fill renderer
+
   return (o1, o2, icorner)
   where
     Point cx cy = ocorner
@@ -530,30 +579,31 @@
 drawRoundedCorner _ _ _ center _ Nothing Nothing = return points where
   points = (center, center, center, center)
 drawRoundedCorner renderer cor bounds ocenter mrcor ms1 ms2 = do
-  beginPath renderer
+  when (w1 > 0 || w2 > 0) $ do
+    beginPath renderer
 
-  if color1 == color2
-    then setFillColor renderer color1
-    else setFillLinearGradient renderer g1 g2 color1 color2
+    if color1 == color2
+      then setFillColor renderer color1
+      else setFillLinearGradient renderer g1 g2 color1 color2
 
-  if round orad == 0
-    then drawRectArc renderer cor icenter w1 w2
-    else renderArc renderer ocenter orad deg (deg - 90) CCW
+    if round orad == 0
+      then drawRectArc renderer cor icenter w1 w2
+      else renderArc renderer ocenter orad deg (deg - 90) CCW
 
-  renderLineTo renderer o1
+    renderLineTo renderer o1
 
-  if round orad > 0 && round irad > 0
-    then do
-      renderLineTo renderer i1
-      renderArc renderer icenter irad (deg - 90) deg CW
-      renderLineTo renderer i2
-    else do
-      renderLineTo renderer icenter
+    if round orad > 0 && round irad > 0
+      then do
+        renderLineTo renderer i1
+        renderArc renderer icenter irad (deg - 90) deg CW
+        renderLineTo renderer i2
+      else do
+        renderLineTo renderer icenter
 
-  renderLineTo renderer o2
+    renderLineTo renderer o2
 
-  closePath renderer
-  fill renderer
+    closePath renderer
+    fill renderer
 
   return bordersCorners
   where
@@ -619,15 +669,16 @@
 
 drawQuad :: Renderer -> Point -> Point -> Point -> Point -> Maybe BorderSide -> IO ()
 drawQuad renderer p1 p2 p3 p4 Nothing = pure ()
-drawQuad renderer p1 p2 p3 p4 (Just BorderSide{..}) = do
-  beginPath renderer
-  setFillColor renderer _bsColor
-  moveTo renderer p1
-  renderLineTo renderer p2
-  renderLineTo renderer p3
-  renderLineTo renderer p4
-  closePath renderer
-  fill renderer
+drawQuad renderer p1 p2 p3 p4 (Just BorderSide{..}) =
+  when (_bsWidth > 0) $ do
+    beginPath renderer
+    setFillColor renderer _bsColor
+    moveTo renderer p1
+    renderLineTo renderer p2
+    renderLineTo renderer p3
+    renderLineTo renderer p4
+    closePath renderer
+    fill renderer
 
 cornerGradientPoints :: Point -> Point -> (Point, Point)
 cornerGradientPoints outer inner = (g1, g2) where
diff --git a/src/Monomer/Widgets/Util/Theme.hs b/src/Monomer/Widgets/Util/Theme.hs
--- a/src/Monomer/Widgets/Util/Theme.hs
+++ b/src/Monomer/Widgets/Util/Theme.hs
@@ -8,6 +8,7 @@
 
 Helper functions for loading theme values.
 -}
+{-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE Strict #-}
 
@@ -73,3 +74,84 @@
   active = wenv ^. L.theme . L.active . L.userStyleMap . at name
   disabled = wenv ^. L.theme . L.disabled . L.userStyleMap . at name
   style = Style basic hover focus focusHover active disabled
+
+{-|
+Sets the given value, overwriting the previous one, for each of the states of a
+theme.
+
+Useful for customizing a base theme.
+
+@
+theme = darkTheme
+  & setThemeValue L.sliderRadius (Just 10)
+  & setThemeValue L.sliderWidth 10
+@
+-}
+setThemeValue
+  :: Lens' ThemeState a
+  -> a
+  -> Theme
+  -> Theme
+setThemeValue field value theme = newTheme where
+  newTheme = theme
+    & L.basic . field .~ value
+    & L.hover . field .~ value
+    & L.focus . field .~ value
+    & L.focusHover . field .~ value
+    & L.active . field .~ value
+    & L.disabled . field .~ value
+
+{-|
+Sets the given style options, overwriting the previous style, for each of the
+states of a theme.
+
+Useful for customizing a base theme.
+
+@
+theme = darkTheme
+  & setThemeStyle L.dropdownStyle [padding 6, paddingV 6]
+@
+
+Note: In most cases 'mergeThemeStyle' is a better choice, since it keeps all the
+other style settings intact.
+-}
+setThemeStyle
+  :: Lens' ThemeState StyleState
+  -> [StyleState]
+  -> Theme
+  -> Theme
+setThemeStyle field styles theme = newTheme where
+  !value = mconcat styles
+  newTheme = theme
+    & L.basic . field .~ value
+    & L.hover . field .~ value
+    & L.focus . field .~ value
+    & L.focusHover . field .~ value
+    & L.active . field .~ value
+    & L.disabled . field .~ value
+
+{-|
+Merges the given style options with the existing style, for each of the states
+of a theme.
+
+Useful for customizing a base theme.
+
+@
+theme = darkTheme
+  & mergeThemeStyle L.dropdownStyle [padding 6, paddingV 6]
+@
+-}
+mergeThemeStyle
+  :: Lens' ThemeState StyleState
+  -> [StyleState]
+  -> Theme
+  -> Theme
+mergeThemeStyle field styles theme = newTheme where
+  !value = mconcat styles
+  newTheme = theme
+    & L.basic . field <>~ value
+    & L.hover . field <>~ value
+    & L.focus . field <>~ value
+    & L.focusHover . field <>~ value
+    & L.active . field <>~ value
+    & L.disabled . field <>~ value
diff --git a/test/unit/Monomer/Widgets/Containers/BoxSpec.hs b/test/unit/Monomer/Widgets/Containers/BoxSpec.hs
--- a/test/unit/Monomer/Widgets/Containers/BoxSpec.hs
+++ b/test/unit/Monomer/Widgets/Containers/BoxSpec.hs
@@ -26,6 +26,7 @@
 import Monomer.TestEventUtil
 import Monomer.TestUtil
 import Monomer.Widgets.Containers.Box
+import Monomer.Widgets.Containers.Grid
 import Monomer.Widgets.Containers.ZStack
 import Monomer.Widgets.Singles.Button
 import Monomer.Widgets.Singles.Label
@@ -45,6 +46,7 @@
 spec :: Spec
 spec = describe "Box" $ do
   mergeReq
+  filterEvent
   handleEvent
   handleEventIgnoreEmpty
   handleEventSinkEmpty
@@ -74,6 +76,29 @@
     mergeWith newNode oldNode = result ^?! L.node . L.children . ix 0 where
       oldNode2 = nodeInit wenv oldNode
       result = widgetMerge (newNode ^. L.widget) wenv newNode oldNode2
+
+filterEvent :: Spec
+filterEvent = describe "filterEvent" $ do
+  it "should click the first button, since the click event was directed to it" $
+    evts False [evtClick point1] `shouldBe` Seq.singleton (BtnClick 1)
+
+  it "should click the second button, since the click event's target was modified" $
+    evts True [evtClick point1] `shouldBe` Seq.singleton (BtnClick 2)
+
+  where
+    wenv = mockWenv ()
+    point1 = Point 320 200
+    point2 = Point 320 400
+
+    filterEvent wenv node target evt = Just (target & ix 2 .~ 1, evtClick point2)
+
+    btnBox ignore = box_ (expandContent : [boxFilterEvent filterEvent | ignore]) $
+      vgrid [
+        button "Button 1" (BtnClick 1),
+        button "Button 2" (BtnClick 2)
+      ]
+    evts ignore es = nodeHandleEventEvts wenv es $
+      nodeInit wenv (btnBox ignore)
 
 handleEvent :: Spec
 handleEvent = describe "handleEvent" $ do
diff --git a/test/unit/Monomer/Widgets/Containers/ScrollSpec.hs b/test/unit/Monomer/Widgets/Containers/ScrollSpec.hs
--- a/test/unit/Monomer/Widgets/Containers/ScrollSpec.hs
+++ b/test/unit/Monomer/Widgets/Containers/ScrollSpec.hs
@@ -53,6 +53,7 @@
   handleBarClick
   handleThumbDrag
   handleChildrenFocus
+  handleWheel
   handleNestedWheel
   handleMessageReset
   raiseOnChange
@@ -167,6 +168,47 @@
     followNode = scroll stackNode
     evtsIgnore es = nodeHandleEventEvts wenv es ignoreNode
     evtsFollow es = nodeHandleEventEvts wenv es followNode
+
+handleWheel :: Spec
+handleWheel = describe "handleWheel" $ do
+  it "should scroll horizontally with the horizontal wheel and click the second button" $ do
+    eventsH False `shouldBe` Seq.fromList [Button2]
+
+  it "should scroll horizontally with the horizontal wheel, ignoring shift, and click the second button" $ do
+    eventsH True `shouldBe` Seq.fromList [Button2]
+
+  it "should scroll vertically with the vertical wheel and click the third button" $ do
+    eventsV False `shouldBe` Seq.fromList [Button3]
+
+  it "should scroll horizontally with the vertical wheel, since shift is pressed, and click the second button" $ do
+    eventsV True `shouldBe` Seq.fromList [Button2]
+
+  where
+    wenv shiftPressed = mockWenv ()
+      & L.windowSize .~ Size 640 480
+      & L.inputStatus . L.keyMod . L.leftShift .~ shiftPressed
+
+    point = Point 160 240
+    st = [width 640, height 480]
+    stackNode = vstack [
+        hstack [
+          button "Button 1" Button1 `styleBasic` st,
+          button "Button 2" Button2 `styleBasic` st
+        ],
+        hstack [
+          button "Button 3" Button3 `styleBasic` st,
+          button "Button 4" Button4 `styleBasic` st
+        ]
+      ]
+    scrollNode = scroll stackNode
+
+    eventsH shift = nodeHandleEventEvts (wenv shift) es scrollNode where
+      evtWheel = WheelScroll point (Point (-2000) 0) WheelNormal
+      es = [evtWheel, evtClick point]
+
+    eventsV shift = nodeHandleEventEvts (wenv shift) es scrollNode where
+      evtWheel = WheelScroll point (Point 0 (-2000)) WheelNormal
+      es = [evtWheel, evtClick point]
 
 handleNestedWheel :: Spec
 handleNestedWheel = describe "handleNestedWheel" $ do
diff --git a/test/unit/Monomer/Widgets/Singles/ImageSpec.hs b/test/unit/Monomer/Widgets/Singles/ImageSpec.hs
--- a/test/unit/Monomer/Widgets/Singles/ImageSpec.hs
+++ b/test/unit/Monomer/Widgets/Singles/ImageSpec.hs
@@ -36,10 +36,11 @@
   it "should not create a task when merging to the same path" $
     Seq.length reqs2 `shouldBe` 0
 
-  it "should create a task when merging to a different path" $ do
-    Seq.length reqs3 `shouldBe` 2
-    Seq.index reqs3 0 `shouldSatisfy` isRemoveRendererImage
-    Seq.index reqs3 1 `shouldSatisfy` isRunTask
+  it "should create two tasks when merging to a different path" $ do
+    Seq.length reqs3 `shouldBe` 3
+    Seq.index reqs3 0 `shouldSatisfy` isRunTask
+    Seq.index reqs3 1 `shouldSatisfy` isRemoveRendererImage
+    Seq.index reqs3 2 `shouldSatisfy` isRunTask
 
   it "should have one widgetId on init (loading)" $
     ctx1 ^. L.widgetPaths `shouldSatisfy` (== 1) . length