diff --git a/timeplot.cabal b/timeplot.cabal
--- a/timeplot.cabal
+++ b/timeplot.cabal
@@ -1,5 +1,5 @@
 name: timeplot
-version: 0.2.20
+version: 0.2.21
 cabal-version: >=1.6
 build-type: Simple
 license: BSD3
@@ -21,9 +21,16 @@
     type: git
     location: git://github.com/jkff/timeplot.git
 
+flag gtk
+    description: enable output to a gtk window (-of x)
+    default: False
+
 executable tplot
     main-is: Tools/TimePlot.hs
     buildable: True
+    if flag(gtk)
+      cpp-options: -DHAVE_GTK
+    ghc-options: -O2
     other-modules: Graphics.Rendering.Chart.Event
     build-depends: Chart >=0.14, base >=3 && <5, bytestring -any,
                    bytestring-lexing -any, cairo -any, colour -any, containers -any,