diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+# v7.2.2 (2026-05-01)
+
+## ✨ New Features
+
+## 🐛 Bug Fixes
+
+## 🏗️ Architecture Changes
+
 # v7.2.1 (2026-04-30)
 
 ## ✨ New Features
diff --git a/restman.cabal b/restman.cabal
--- a/restman.cabal
+++ b/restman.cabal
@@ -1,6 +1,6 @@
 cabal-version:      1.12
 name:               restman
-version:            0.7.2.1
+version:            0.7.2.2
 license:            BSD2
 license-file:       LICENSE
 copyright:          Zac Slade or Boyd Stephen Smith Jr, 2024
@@ -100,6 +100,7 @@
         base >=4.7 && <5,
         brick >=2.9 && <2.10,
         bytestring >=0.12.2.0 && <0.13,
+        case-insensitive >=1.2.1.0 && <1.3,
         containers >=0.7 && <0.8,
         hedgehog >=1.5 && <1.6,
         http-client >=0.7.19 && <0.8,
diff --git a/src/Lib.hs b/src/Lib.hs
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -21,7 +21,9 @@
     , lbsToText
     , moveFocusNext
     , moveFocusPrev
+    , noSyntaxFound
     , splitExtraSpace
+    , syntaxHighlightResponse
     ) where
 
 -- base
diff --git a/src/Skylighting/Format/Vty.hs b/src/Skylighting/Format/Vty.hs
--- a/src/Skylighting/Format/Vty.hs
+++ b/src/Skylighting/Format/Vty.hs
@@ -11,6 +11,7 @@
        , attrStyle
        , attrColor
        , colorDistance
+       , vtyStyleAttr
        ) where
 import Control.Monad (mplus)
 import Data.Binary (Binary)
diff --git a/test/HTTP/ClientSpec.hs b/test/HTTP/ClientSpec.hs
--- a/test/HTTP/ClientSpec.hs
+++ b/test/HTTP/ClientSpec.hs
@@ -6,12 +6,15 @@
 import Test.Tasty
 import Test.Tasty.HUnit
 
-import HTTP.Client (UseDefaultHeaders(..), knownMethods)
+import qualified Network.HTTP.Client as HC
 
+import HTTP.Client (UseDefaultHeaders(..), knownMethods, robustSettings)
+
 tests :: TestTree
 tests = testGroup "HTTP.Client"
   [ knownMethodsTests
   , useDefaultHeadersTests
+  , robustSettingsTests
   ]
 
 -- ---------------------------------------------------------------------------
@@ -83,4 +86,24 @@
   , testCase "Enum: sorted [minBound..maxBound] equals [minBound..maxBound]" $
       sort [minBound .. maxBound :: UseDefaultHeaders]
         @?= [minBound .. maxBound]
+  , testCase "Enum: fromEnum ReplaceDefaultHeaders == 0" $
+      fromEnum ReplaceDefaultHeaders @?= 0
+  , testCase "Enum: fromEnum AppendCustomToDefaultHeaders == 1" $
+      fromEnum AppendCustomToDefaultHeaders @?= 1
+  , testCase "Enum: succ ReplaceDefaultHeaders == AppendCustomToDefaultHeaders" $
+      succ ReplaceDefaultHeaders @?= AppendCustomToDefaultHeaders
+  , testCase "Enum: pred AppendCustomToDefaultHeaders == ReplaceDefaultHeaders" $
+      pred AppendCustomToDefaultHeaders @?= ReplaceDefaultHeaders
+  ]
+
+-- ---------------------------------------------------------------------------
+-- robustSettings
+-- ---------------------------------------------------------------------------
+
+robustSettingsTests :: TestTree
+robustSettingsTests = testGroup "robustSettings"
+  [ testCase "can create a manager from robustSettings without error" $ do
+      mgr <- HC.newManager robustSettings
+      -- Just confirm the manager was created; destroy it immediately.
+      HC.closeManager mgr
   ]
diff --git a/test/LibSpec.hs b/test/LibSpec.hs
--- a/test/LibSpec.hs
+++ b/test/LibSpec.hs
@@ -1,6 +1,9 @@
 {-# language OverloadedStrings #-}
 module LibSpec (tests) where
 
+import Data.Maybe (isJust, isNothing)
+
+import qualified Data.ByteString as BS
 import qualified Data.ByteString.Lazy as LBS
 import qualified Data.Text as Text
 
@@ -9,20 +12,36 @@
 
 import qualified Network.HTTP.Client as HC
 
+import Brick.Types (CursorLocation(..), Location(..))
+import Brick.Widgets.Edit (getEditContents)
+import qualified Data.CaseInsensitive as CI
+
 import Graphics.Vty.Attributes
   (Attr(attrStyle), MaybeDefault(..), Style, currentAttr, reverseVideo)
+import qualified Graphics.Vty.Attributes as VA
+import Graphics.Vty.Image (charFill, emptyImage, imageHeight, imageWidth)
 
 import HTTP.Client (UseDefaultHeaders(..))
 import Lib
-  ( cleanPayload
+  ( chooseCursor
+  , cleanPayload
   , focusAttr
   , focusStyle
+  , growWith
   , lbsToText
   , moveFocusNext
   , moveFocusPrev
+  , noSyntaxFound
   , splitExtraSpace
+  , syntaxHighlightResponse
   )
-import Types (AppR(..), AppS(..), RangeInAlign(..))
+import Types
+  ( AppR(..)
+  , AppS(..)
+  , CustomHeaderColumn(..)
+  , CustomHeaderR(..)
+  , RangeInAlign(..)
+  )
 import UI (mkInitialState)
 
 tests :: TestTree
@@ -34,6 +53,11 @@
   , focusAttrTests
   , moveFocusNextTests
   , moveFocusPrevTests
+  , moveFocusNextCustomHeaderTests
+  , moveFocusPrevCustomHeaderTests
+  , growSpacesTests
+  , chooseCursorTests
+  , syntaxHighlightResponseTests
   ]
 
 -- ---------------------------------------------------------------------------
@@ -116,6 +140,12 @@
       cleanPayload "line1\nline2" @?= "line1\nline2"
   , testCase "carriage return is preserved" $
       cleanPayload "foo\rbar" @?= "foo\rbar"
+  , testCase "only special chars gives empty output" $
+      cleanPayload "\ESC\v" @?= Text.empty
+  , testCase "ESC and vtab together are both stripped" $
+      cleanPayload "\ESC\vhello" @?= "hello"
+  , testCase "tab followed by ESC: tab expands, ESC stripped" $
+      cleanPayload "\t\ESC" @?= "    "
   ]
 
 -- ---------------------------------------------------------------------------
@@ -203,6 +233,11 @@
       let s = withFocus ResponseBodyView
                 (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
       focus (moveFocusNext s) @?= MethodEditor
+  , testCase "MethodSelector -> MethodEditor (invalid focus)" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = withFocus MethodSelector
+                (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+      focus (moveFocusNext s) @?= MethodEditor
   ]
  where
   withFocus f s = s { focus = f }
@@ -239,6 +274,214 @@
       let s = withFocus ResponseBodyView
                 (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
       focus (moveFocusPrev s) @?= AddCustomHeader
+  , testCase "MethodSelector -> ResponseBodyView (invalid focus)" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = withFocus MethodSelector
+                (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+      focus (moveFocusPrev s) @?= ResponseBodyView
   ]
  where
   withFocus f s = s { focus = f }
+
+-- ---------------------------------------------------------------------------
+-- moveFocusNext / moveFocusPrev with custom headers
+-- ---------------------------------------------------------------------------
+
+-- One fake header
+oneHeader :: [(Bool, (CI.CI BS.ByteString, BS.ByteString))]
+oneHeader = [(True, (CI.mk "X-Test", "value"))]
+
+-- Two fake headers
+twoHeaders :: [(Bool, (CI.CI BS.ByteString, BS.ByteString))]
+twoHeaders = [ (True, (CI.mk "X-First", "one"))
+             , (True, (CI.mk "X-Second", "two"))
+             ]
+
+moveFocusNextCustomHeaderTests :: TestTree
+moveFocusNextCustomHeaderTests = testGroup "moveFocusNext (custom headers)"
+  [ testCase "DefaultHeadersToggle -> ExistingCustomHeader 0 ActiveToggle (with 1 header)" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = DefaultHeadersToggle, customHeaders = oneHeader }
+      focus (moveFocusNext s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = ActiveToggle })
+  , testCase "ExistingCustomHeader 0 ActiveToggle -> NameEditor" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 ActiveToggle)
+                , customHeaders = oneHeader }
+      focus (moveFocusNext s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = NameEditor })
+  , testCase "ExistingCustomHeader 0 NameEditor -> ValueEditor" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 NameEditor)
+                , customHeaders = oneHeader }
+      focus (moveFocusNext s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = ValueEditor })
+  , testCase "ExistingCustomHeader 0 ValueEditor (last header) -> AddCustomHeader" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 ValueEditor)
+                , customHeaders = oneHeader }
+      focus (moveFocusNext s) @?= AddCustomHeader
+  , testCase "ExistingCustomHeader 0 ValueEditor (2 headers) -> next header ActiveToggle" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 ValueEditor)
+                , customHeaders = twoHeaders }
+      focus (moveFocusNext s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 1, column = ActiveToggle })
+  ]
+
+moveFocusPrevCustomHeaderTests :: TestTree
+moveFocusPrevCustomHeaderTests = testGroup "moveFocusPrev (custom headers)"
+  [ testCase "AddCustomHeader -> ExistingCustomHeader 0 ValueEditor (1 header)" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = AddCustomHeader, customHeaders = oneHeader }
+      focus (moveFocusPrev s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = ValueEditor })
+  , testCase "ExistingCustomHeader 0 NameEditor -> ActiveToggle" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 NameEditor)
+                , customHeaders = oneHeader }
+      focus (moveFocusPrev s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = ActiveToggle })
+  , testCase "ExistingCustomHeader 0 ValueEditor -> NameEditor" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 ValueEditor)
+                , customHeaders = oneHeader }
+      focus (moveFocusPrev s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = NameEditor })
+  , testCase "ExistingCustomHeader 0 ActiveToggle (first header) -> DefaultHeadersToggle" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 0 ActiveToggle)
+                , customHeaders = oneHeader }
+      focus (moveFocusPrev s) @?= DefaultHeadersToggle
+  , testCase "ExistingCustomHeader 1 ActiveToggle -> previous header ValueEditor" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { focus = ExistingCustomHeader (MkCustomHeaderR 1 ActiveToggle)
+                , customHeaders = twoHeaders }
+      focus (moveFocusPrev s) @?=
+        ExistingCustomHeader (MkCustomHeaderR { listIndex = 0, column = ValueEditor })
+  ]
+
+-- ---------------------------------------------------------------------------
+-- growWith / growSpaces
+-- ---------------------------------------------------------------------------
+
+growSpacesTests :: TestTree
+growSpacesTests = testGroup "growSpaces"
+  [ testCase "grow emptyImage to 5 wide 3 tall: width == 5" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 5 Min 3 Min emptyImage
+      imageWidth img @?= 5
+  , testCase "grow emptyImage to 5 wide 3 tall: height == 3" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 5 Min 3 Min emptyImage
+      imageHeight img @?= 3
+  , testCase "grow to 0 wide 0 tall is a no-op on emptyImage" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 0 Min 0 Min emptyImage
+      imageWidth img @?= 0
+      imageHeight img @?= 0
+  , testCase "image already wider than min: width unchanged" $ do
+      let src = charFill VA.currentAttr '*' 10 1
+          img = growWith (charFill VA.currentAttr ' ') 5 Min 1 Min src
+      imageWidth img @?= 10
+  , testCase "image already taller than min: height unchanged" $ do
+      let src = charFill VA.currentAttr '*' 1 10
+          img = growWith (charFill VA.currentAttr ' ') 1 Min 5 Min src
+      imageHeight img @?= 10
+  , testCase "Max wide alignment: grows to min width" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 10 Max 1 Min (charFill VA.currentAttr '*' 2 1)
+      imageWidth img @?= 10
+  , testCase "Max vert alignment: grows to min height" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 1 Min 5 Max (charFill VA.currentAttr '*' 1 2)
+      imageHeight img @?= 5
+  , testCase "MidL wide alignment: grows to min width" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 6 MidL 1 Min (charFill VA.currentAttr '*' 2 1)
+      imageWidth img @?= 6
+  , testCase "MidG wide alignment: grows to min width" $ do
+      let img = growWith (charFill VA.currentAttr ' ') 6 MidG 1 Min (charFill VA.currentAttr '*' 2 1)
+      imageWidth img @?= 6
+  ]
+
+-- ---------------------------------------------------------------------------
+-- chooseCursor
+-- ---------------------------------------------------------------------------
+
+chooseCursorTests :: TestTree
+chooseCursorTests = testGroup "chooseCursor"
+  [ testCase "no overlay, empty cursor list -> Nothing" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing
+      assertBool "expected Nothing" (isNothing (chooseCursor s []))
+  , testCase "no overlay, UrlEditor cursor in list -> returns it" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing
+          loc = CursorLocation (Location (0, 0)) (Just UrlEditor) True
+          result = chooseCursor s [loc]
+      assertBool "expected Just" (isJust result)
+  , testCase "no overlay, wrong name cursor -> Nothing" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing
+          loc = CursorLocation (Location (0, 0)) (Just MethodEditor) True
+      assertBool "expected Nothing" (isNothing (chooseCursor s [loc]))
+  , testCase "overlay present, empty cursor list -> Nothing" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { overlayState = Just undefined }
+      assertBool "expected Nothing" (isNothing (chooseCursor s []))
+  , testCase "overlay present, MethodSelector cursor -> returns it" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { overlayState = Just undefined }
+          loc = CursorLocation (Location (0, 0)) (Just MethodSelector) True
+          result = chooseCursor s [loc]
+      assertBool "expected Just" (isJust result)
+  , testCase "overlay present, non-MethodSelector cursor -> Nothing" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = (mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing)
+                { overlayState = Just undefined }
+          loc = CursorLocation (Location (0, 0)) (Just UrlEditor) True
+      assertBool "expected Nothing" (isNothing (chooseCursor s [loc]))
+  ]
+
+-- ---------------------------------------------------------------------------
+-- syntaxHighlightResponse / noSyntaxFound
+-- ---------------------------------------------------------------------------
+
+syntaxHighlightResponseTests :: TestTree
+syntaxHighlightResponseTests = testGroup "syntaxHighlightResponse"
+  [ testCase "Nothing payload -> non-empty 'no response body' image" $ do
+      let img = syntaxHighlightResponse Nothing Nothing
+      assertBool "expected non-empty image" (imageWidth img > 0 || imageHeight img > 0)
+  , testCase "Just payload, Nothing content-type -> non-empty image" $ do
+      let img = syntaxHighlightResponse (Just "hello world") Nothing
+      assertBool "expected non-empty image" (imageWidth img > 0 || imageHeight img > 0)
+  , testCase "Just payload, Just application/json content-type -> non-empty image" $ do
+      let img = syntaxHighlightResponse (Just "{\"a\":1}") (Just "application/json")
+      assertBool "expected non-empty image" (imageWidth img > 0 || imageHeight img > 0)
+  , testCase "Just payload, Just unknown content-type -> same height as noSyntaxFound" $ do
+      let img = syntaxHighlightResponse (Just "data") (Just "application/x-unknown-restman-test")
+          img2 = noSyntaxFound "data"
+      imageHeight img @?= imageHeight img2
+  , testCase "Just payload, Just text/plain content-type -> non-empty image" $ do
+      let img = syntaxHighlightResponse (Just "hello world") (Just "text/plain")
+      assertBool "expected non-empty image" (imageWidth img > 0 || imageHeight img > 0)
+  , testCase "Just payload, Just text/html content-type -> non-empty image" $ do
+      let img = syntaxHighlightResponse (Just "<p>hello</p>") (Just "text/html")
+      assertBool "expected non-empty image" (imageWidth img > 0 || imageHeight img > 0)
+  , testCase "noSyntaxFound empty text -> non-empty image (header line)" $ do
+      let img = noSyntaxFound Text.empty
+      assertBool "expected non-empty image" (imageWidth img > 0 || imageHeight img > 0)
+  , testCase "noSyntaxFound single-line text -> height is 2 (header + 1 line)" $ do
+      let img = noSyntaxFound "hello world"
+      imageHeight img @?= 2
+  , testCase "noSyntaxFound two-line text -> height is 3 (header + 2 lines)" $ do
+      let img = noSyntaxFound "line1\nline2"
+      imageHeight img @?= 3
+  ]
diff --git a/test/Props/LibProps.hs b/test/Props/LibProps.hs
--- a/test/Props/LibProps.hs
+++ b/test/Props/LibProps.hs
@@ -1,12 +1,13 @@
 {-# language OverloadedStrings #-}
 module Props.LibProps (tests) where
 
--- base
-import Data.List (foldl')
-
 -- bytestring
+import qualified Data.ByteString as BS
 import qualified Data.ByteString.Lazy as LBS
 
+-- case-insensitive
+import qualified Data.CaseInsensitive as CI
+
 -- hedgehog
 import Hedgehog
 import qualified Hedgehog.Gen as Gen
@@ -25,12 +26,15 @@
 
 -- vty
 import Graphics.Vty.Attributes (Style, reverseVideo)
+import qualified Graphics.Vty.Attributes as VA
+import Graphics.Vty.Image (charFill, imageHeight, imageWidth)
 
 -- restman
-import HTTP.Client (UseDefaultHeaders(..))
+import HTTP.Client (Header, UseDefaultHeaders(..))
 import Lib
   ( cleanPayload
   , focusStyle
+  , growWith
   , lbsToText
   , moveFocusNext
   , moveFocusPrev
@@ -46,6 +50,7 @@
   , lbsToTextProps
   , focusStyleProps
   , focusCycleProps
+  , growSpacesProps
   ]
 
 -- ---------------------------------------------------------------------------
@@ -185,10 +190,17 @@
   _ <- evalNF (lbsToText bs)
   success
 
+-- Valid Unicode text encoded as UTF-8 decodes back to itself.
+prop_lbsToText_unicode_roundtrip :: Property
+prop_lbsToText_unicode_roundtrip = property $ do
+  t <- forAll $ Gen.text (Range.linear 0 100) Gen.unicode
+  lbsToText (LBS.fromStrict $ encodeUtf8 t) === t
+
 lbsToTextProps :: TestTree
 lbsToTextProps = testGroup "lbsToText"
   [ testProperty "ASCII encode/decode roundtrip" prop_lbsToText_ascii_roundtrip
   , testProperty "never throws on arbitrary bytes" prop_lbsToText_never_throws
+  , testProperty "valid Unicode encode/decode roundtrip" prop_lbsToText_unicode_roundtrip
   ]
 
 -- ---------------------------------------------------------------------------
@@ -265,9 +277,85 @@
   let s1 = s0 { focus = startFocus }
   focus (moveFocusPrev (moveFocusNext s1)) === startFocus
 
+-- Applying moveFocusNext 8 times with one custom header returns focus to its
+-- starting position (5 non-header stops + 3 per header = 8 total).
+prop_moveFocusNext_cycle8_one_header :: Property
+prop_moveFocusNext_cycle8_one_header = property $ do
+  mgr <- evalIO $ HC.newManager HC.defaultManagerSettings
+  let oneHeader :: [Header]
+      oneHeader = [(CI.mk ("X-Test" :: BS.ByteString), "value")]
+      s0 = mkInitialState mgr "GET" ReplaceDefaultHeaders oneHeader Nothing Nothing
+      sN = foldl' (flip ($)) s0 (replicate 8 moveFocusNext)
+  focus sN === focus s0
+
 focusCycleProps :: TestTree
 focusCycleProps = testGroup "focus cycle"
   [ testProperty "moveFocusNext: 5 steps is full cycle"              prop_moveFocusNext_cycle5
   , testProperty "moveFocusPrev: 5 steps is full cycle"              prop_moveFocusPrev_cycle5
   , testProperty "moveFocusNext then moveFocusPrev restores focus"   prop_moveFocusNext_then_prev_identity
+  , testProperty "moveFocusNext: 8 steps with 1 header is full cycle" prop_moveFocusNext_cycle8_one_header
+  ]
+
+-- ---------------------------------------------------------------------------
+-- growWith / growSpaces properties
+--
+-- growWith fillImg minW wa minH va img
+-- Post-conditions: output width >= max(minW, imageWidth img)
+--                  output height >= max(minH, imageHeight img)
+-- ---------------------------------------------------------------------------
+
+-- Output width is always at least the requested minimum.
+prop_growSpaces_width_ge_min :: Property
+prop_growSpaces_width_ge_min = property $ do
+  minW <- forAll $ Gen.int (Range.linear 0 50)
+  minH <- forAll $ Gen.int (Range.linear 1 50)
+  srcW <- forAll $ Gen.int (Range.linear 1 50)
+  srcH <- forAll $ Gen.int (Range.linear 1 50)
+  align <- forAll genAlign
+  let src = charFill VA.currentAttr ' ' srcW srcH
+      img = growWith (charFill VA.currentAttr ' ') minW align minH align src
+  assert (imageWidth img >= minW)
+
+-- Output height is always at least the requested minimum.
+prop_growSpaces_height_ge_min :: Property
+prop_growSpaces_height_ge_min = property $ do
+  minW <- forAll $ Gen.int (Range.linear 1 50)
+  minH <- forAll $ Gen.int (Range.linear 0 50)
+  srcW <- forAll $ Gen.int (Range.linear 1 50)
+  srcH <- forAll $ Gen.int (Range.linear 1 50)
+  align <- forAll genAlign
+  let src = charFill VA.currentAttr ' ' srcW srcH
+      img = growWith (charFill VA.currentAttr ' ') minW align minH align src
+  assert (imageHeight img >= minH)
+
+-- Output width is always at least the source image width.
+prop_growSpaces_width_ge_src :: Property
+prop_growSpaces_width_ge_src = property $ do
+  minW <- forAll $ Gen.int (Range.linear 0 50)
+  minH <- forAll $ Gen.int (Range.linear 1 50)
+  srcW <- forAll $ Gen.int (Range.linear 1 50)
+  srcH <- forAll $ Gen.int (Range.linear 1 50)
+  align <- forAll genAlign
+  let src = charFill VA.currentAttr ' ' srcW srcH
+      img = growWith (charFill VA.currentAttr ' ') minW align minH align src
+  assert (imageWidth img >= imageWidth src)
+
+-- Output height is always at least the source image height.
+prop_growSpaces_height_ge_src :: Property
+prop_growSpaces_height_ge_src = property $ do
+  minW <- forAll $ Gen.int (Range.linear 1 50)
+  minH <- forAll $ Gen.int (Range.linear 0 50)
+  srcW <- forAll $ Gen.int (Range.linear 1 50)
+  srcH <- forAll $ Gen.int (Range.linear 1 50)
+  align <- forAll genAlign
+  let src = charFill VA.currentAttr ' ' srcW srcH
+      img = growWith (charFill VA.currentAttr ' ') minW align minH align src
+  assert (imageHeight img >= imageHeight src)
+
+growSpacesProps :: TestTree
+growSpacesProps = testGroup "growSpaces"
+  [ testProperty "output width >= requested minimum"  prop_growSpaces_width_ge_min
+  , testProperty "output height >= requested minimum" prop_growSpaces_height_ge_min
+  , testProperty "output width >= source width"       prop_growSpaces_width_ge_src
+  , testProperty "output height >= source height"     prop_growSpaces_height_ge_src
   ]
diff --git a/test/Props/SkylightingProps.hs b/test/Props/SkylightingProps.hs
--- a/test/Props/SkylightingProps.hs
+++ b/test/Props/SkylightingProps.hs
@@ -20,13 +20,15 @@
 import Skylighting.Types (ANSIColorLevel(..), Color(..))
 
 -- restman
-import Skylighting.Format.Vty (attrColor, attrStyle, colorDistance)
+import Skylighting.Format.Vty
+  (attrColor, attrStyle, colorDistance, vtyStyleAttr)
 
 tests :: TestTree
 tests = testGroup "Props.Skylighting.Format.Vty"
   [ colorDistanceProps
   , attrStyleProps
   , attrColorProps
+  , vtyStyleAttrProps
   ]
 
 -- ---------------------------------------------------------------------------
@@ -183,4 +185,77 @@
   [ testProperty "Nothing -> Nothing for all levels"  prop_attrColor_nothing_to_nothing
   , testProperty "Just -> Just for all levels"        prop_attrColor_just_to_just
   , testProperty "same input gives same output"       prop_attrColor_same_rgb_same_result
+  ]
+
+-- ---------------------------------------------------------------------------
+-- vtyStyleAttr properties
+--
+-- vtyStyleAttr :: ANSIColorLevel -> Maybe Color -> Maybe Color
+--              -> Bool -> Bool -> Bool -> VA.Attr
+-- ---------------------------------------------------------------------------
+
+-- fg Nothing -> attrForeColor is Default.
+prop_vtyStyleAttr_fg_nothing_default :: Property
+prop_vtyStyleAttr_fg_nothing_default = property $ do
+  clv <- forAll genColorLevel
+  bgc <- forAll (Gen.maybe genColor)
+  b   <- forAll Gen.bool
+  i   <- forAll Gen.bool
+  u   <- forAll Gen.bool
+  VA.attrForeColor (vtyStyleAttr clv Nothing bgc b i u) === VA.Default
+
+-- fg Just -> attrForeColor is SetTo.
+prop_vtyStyleAttr_fg_just_set :: Property
+prop_vtyStyleAttr_fg_just_set = property $ do
+  clv <- forAll genColorLevel
+  fgc <- forAll genColor
+  bgc <- forAll (Gen.maybe genColor)
+  b   <- forAll Gen.bool
+  i   <- forAll Gen.bool
+  u   <- forAll Gen.bool
+  case VA.attrForeColor (vtyStyleAttr clv (Just fgc) bgc b i u) of
+    VA.SetTo _ -> success
+    _ -> failure
+
+-- bg Nothing -> attrBackColor is Default.
+prop_vtyStyleAttr_bg_nothing_default :: Property
+prop_vtyStyleAttr_bg_nothing_default = property $ do
+  clv <- forAll genColorLevel
+  fgc <- forAll (Gen.maybe genColor)
+  b   <- forAll Gen.bool
+  i   <- forAll Gen.bool
+  u   <- forAll Gen.bool
+  VA.attrBackColor (vtyStyleAttr clv fgc Nothing b i u) === VA.Default
+
+-- bg Just -> attrBackColor is SetTo.
+prop_vtyStyleAttr_bg_just_set :: Property
+prop_vtyStyleAttr_bg_just_set = property $ do
+  clv <- forAll genColorLevel
+  fgc <- forAll (Gen.maybe genColor)
+  bgc <- forAll genColor
+  b   <- forAll Gen.bool
+  i   <- forAll Gen.bool
+  u   <- forAll Gen.bool
+  case VA.attrBackColor (vtyStyleAttr clv fgc (Just bgc) b i u) of
+    VA.SetTo _ -> success
+    _ -> failure
+
+-- attrURL is always Default.
+prop_vtyStyleAttr_url_always_default :: Property
+prop_vtyStyleAttr_url_always_default = property $ do
+  clv <- forAll genColorLevel
+  fgc <- forAll (Gen.maybe genColor)
+  bgc <- forAll (Gen.maybe genColor)
+  b   <- forAll Gen.bool
+  i   <- forAll Gen.bool
+  u   <- forAll Gen.bool
+  VA.attrURL (vtyStyleAttr clv fgc bgc b i u) === VA.Default
+
+vtyStyleAttrProps :: TestTree
+vtyStyleAttrProps = testGroup "vtyStyleAttr"
+  [ testProperty "fg Nothing -> Default foreground"    prop_vtyStyleAttr_fg_nothing_default
+  , testProperty "fg Just -> SetTo foreground"         prop_vtyStyleAttr_fg_just_set
+  , testProperty "bg Nothing -> Default background"    prop_vtyStyleAttr_bg_nothing_default
+  , testProperty "bg Just -> SetTo background"         prop_vtyStyleAttr_bg_just_set
+  , testProperty "attrURL is always Default"           prop_vtyStyleAttr_url_always_default
   ]
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -20,7 +20,8 @@
   , defaultFormatOpts
   )
 
-import Skylighting.Format.Vty (attrColor, attrStyle, colorDistance, formatVty)
+import Skylighting.Format.Vty
+  (attrColor, attrStyle, colorDistance, formatVty, vtyStyleAttr)
 
 import qualified HTTP.ClientSpec
 import qualified LibSpec
@@ -55,6 +56,7 @@
       , attrColorTests
       , colorDistanceTests
       , formatVtyTests
+      , vtyStyleAttrTests
       ]
   , testGroup "property tests"
       [ Props.HTTPClientProps.tests
@@ -125,4 +127,50 @@
                    }
           img = formatVty opts emptyStyle [[(NormalTok, "hello")]]
       VI.imageWidth img @?= 5
+  , testCase "three source lines has height 3" $ do
+      let opts = defaultFormatOpts { numberLines = False }
+          img = formatVty opts emptyStyle
+                  [ [(NormalTok, "a")]
+                  , [(NormalTok, "b")]
+                  , [(NormalTok, "c")]
+                  ]
+      VI.imageHeight img @?= 3
+  , testCase "number lines enabled produces wider image than without" $ do
+      let optsNums = defaultFormatOpts { numberLines = True,  ansiColorLevel = ANSITrueColor }
+          optsNoNums = defaultFormatOpts { numberLines = False, ansiColorLevel = ANSITrueColor }
+          src = [[(NormalTok, "hello")]]
+          imgNums = formatVty optsNums   emptyStyle src
+          imgNoNums = formatVty optsNoNums emptyStyle src
+      assertBool "image with line numbers should be wider" (VI.imageWidth imgNums > VI.imageWidth imgNoNums)
+  ]
+
+vtyStyleAttrTests :: TestTree
+vtyStyleAttrTests = testGroup "vtyStyleAttr"
+  [ testCase "no color, no style -> all Default except style SetTo defaultStyleMask" $ do
+      let a = vtyStyleAttr ANSITrueColor Nothing Nothing False False False
+      VA.attrStyle a @?= VA.SetTo VA.defaultStyleMask
+      VA.attrForeColor a @?= VA.Default
+      VA.attrBackColor a @?= VA.Default
+  , testCase "fg Just red -> attrForeColor is SetTo" $ do
+      let a = vtyStyleAttr ANSITrueColor (Just (RGB 255 0 0)) Nothing False False False
+      case VA.attrForeColor a of
+        VA.SetTo _ -> pure ()
+        _ -> assertFailure "expected SetTo for fg color"
+  , testCase "bg Just green -> attrBackColor is SetTo" $ do
+      let a = vtyStyleAttr ANSITrueColor Nothing (Just (RGB 0 255 0)) False False False
+      case VA.attrBackColor a of
+        VA.SetTo _ -> pure ()
+        _ -> assertFailure "expected SetTo for bg color"
+  , testCase "bold=True -> bold bit set in style" $ do
+      let a = vtyStyleAttr ANSITrueColor Nothing Nothing True False False
+      VA.attrStyle a @?= VA.SetTo VA.bold
+  , testCase "italic=True -> italic bit set in style" $ do
+      let a = vtyStyleAttr ANSITrueColor Nothing Nothing False True False
+      VA.attrStyle a @?= VA.SetTo VA.italic
+  , testCase "underline=True -> underline bit set in style" $ do
+      let a = vtyStyleAttr ANSITrueColor Nothing Nothing False False True
+      VA.attrStyle a @?= VA.SetTo VA.underline
+  , testCase "attrURL is always Default" $ do
+      let a = vtyStyleAttr ANSITrueColor (Just (RGB 1 2 3)) (Just (RGB 4 5 6)) True True True
+      VA.attrURL a @?= VA.Default
   ]
diff --git a/test/UISpec.hs b/test/UISpec.hs
--- a/test/UISpec.hs
+++ b/test/UISpec.hs
@@ -6,11 +6,15 @@
 import Test.Tasty
 import Test.Tasty.HUnit
 
+import qualified Data.ByteString as BS
+import qualified Data.CaseInsensitive as CI
+
 import qualified Network.HTTP.Client as HC
 
 import Brick.Widgets.Edit (getEditContents)
+import Graphics.Vty.Image (imageWidth)
 
-import HTTP.Client (UseDefaultHeaders(..))
+import HTTP.Client (Header, UseDefaultHeaders(..))
 import Types (AppS(..))
 import UI (mkInitialState)
 
@@ -65,4 +69,19 @@
       mgr <- HC.newManager HC.defaultManagerSettings
       let s = mkInitialState mgr "GET" ReplaceDefaultHeaders [] (Just "request body") Nothing
       payload s @?= Just "request body"
+  , testCase "lastResponse starts as zero-width image" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let s = mkInitialState mgr "GET" ReplaceDefaultHeaders [] Nothing Nothing
+      imageWidth (lastResponse s) @?= 0
+  , testCase "supplied headers are initially active" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let hdr = (CI.mk ("X-Custom" :: BS.ByteString), "val" :: BS.ByteString)
+          s = mkInitialState mgr "GET" ReplaceDefaultHeaders [hdr] Nothing Nothing
+      customHeaders s @?= [(True, hdr)]
+  , testCase "multiple supplied headers count is preserved" $ do
+      mgr <- HC.newManager HC.defaultManagerSettings
+      let hdrs :: [Header]
+          hdrs = [(CI.mk "X-A", "1"), (CI.mk "X-B", "2")]
+          s = mkInitialState mgr "GET" ReplaceDefaultHeaders hdrs Nothing Nothing
+      length (customHeaders s) @?= 2
   ]