--- a/GnuplotGraphView.st	Mon Apr 30 22:12:02 2018 +0200
+++ b/GnuplotGraphView.st	Mon Apr 30 23:26:28 2018 +0200
@@ -1,3 +1,5 @@
+"{ Encoding: utf8 }"
+
 "{ Package: 'stx:libwidg2' }"
 
 "{ NameSpace: Smalltalk }"
@@ -171,11 +173,13 @@
         data:(RandomGenerator new next:50);
         open
     "
-    |command tmpDir outStream errorStream statusCode ok
+    |scriptUsed command tmpDir outStream errorStream statusCode ok
      dataFilename scriptFilename outFilename argsDict expandedScript
      stdout stderr|
 
-    script isNil ifTrue:[^ self].
+    (scriptUsed := script) isNil ifTrue:[
+        scriptUsed := self class defaultScript.
+    ].
 
     command := 'gnuplot "%1"'.
     argsDict := Dictionary new.
@@ -196,7 +200,7 @@
     argsDict at:'outputFormat' put:'png'.
     argsDict at:'title' put:(title ? '').
 
-    expandedScript := script bindWithArguments:argsDict.
+    expandedScript := scriptUsed bindWithArguments:argsDict.
     scriptFilename := (Filename newTemporaryIn:tmpDir).
     scriptFilename := scriptFilename asFilename withSuffix:'gnuplot'.
     scriptFilename contents:expandedScript.
@@ -237,6 +241,28 @@
         self generateImage  
     ].
     super generateMagnifiedImage.
+!
+
+redrawX:x y:y width:w height:h
+    (OperatingSystem canExecuteCommand:'gnuplot') ifFalse:[
+        self clearRectangleX:x y:y width:w height:h.
+        self showWarning.
+        ^ self.
+    ].
+    super redrawX:x y:y width:w height:h.
+!
+
+showWarning
+    |infoMsg wString|
+
+    infoMsg := resources string:'No gnuplot command found'.
+    wString := gc font widthOf:infoMsg.
+    gc displayString:infoMsg x:(self width - wString) // 2 y:(self height // 2).
+!
+
+sizeChanged:how
+    super sizeChanged:how.
+    self invalidate.
 ! !
 
 !GnuplotGraphView class methodsFor:'documentation'!