Fix possible excanvas leak (report and suggested fix by tom9729)

git-svn-id: https://flot.googlecode.com/svn/trunk@284 1e0a6537-2640-0410-bfb7-f154510ff394

NEWS.txt

@@ -111,7 +111,9 @@ Bug fixes:
 - Listen for mouseleave events and fire a plothover event with empty
   item when it occurs to drop highlights when the mouse leaves the
   plot (reported by by outspirit).
-- Fix bug with using aboveData with a background (reported by amitayd).
+- Fix bug with using aboveData with a background (reported by
+  amitayd).
+- Fix possible excanvas leak (report and suggested fix by tom9729).
 
 
 Flot 0.6

jquery.flot.js

@@ -699,15 +699,28 @@
         function constructCanvas() {
             canvasWidth = placeholder.width();
             canvasHeight = placeholder.height();
+
+             // excanvas hack, if there are any canvases here, whack
+             // the state on them manually
+            if (window.G_vmlCanvasManager)
+                placeholder.find("canvas").each(function () {
+                    delete this.context_;
+                });
+            
             placeholder.html(""); // clear placeholder
+            
             if (placeholder.css("position") == 'static')
                 placeholder.css("position", "relative"); // for positioning labels and overlay
 
             if (canvasWidth <= 0 || canvasHeight <= 0)
                 throw "Invalid dimensions for plot, width = " + canvasWidth + ", height = " + canvasHeight;
 
-            if (window.G_vmlCanvasManager) // excanvas hack, make sure everything is setup
+             // excanvas hack, make sure everything is setup
+            if (window.G_vmlCanvasManager
+                && !window.G_vmlCanvasManager.inited) {
+                window.G_vmlCanvasManager.inited = true;
                 window.G_vmlCanvasManager.init_(document);
+            }
             
             function makeCanvas(skipPositioning) {
                 var c = document.createElement('canvas');