Fix crashes on Ubuntu 12.04 caused by overlay scrolll bar causing the drawing

surface to be finished.

2 files changed, 23 insertions, 0 deletions

diff --git a/gtk/PlatGTK.cxx b/gtk/PlatGTK.cxx
index c1e5566e5..d4572a912 100644
--- a/gtk/PlatGTK.cxx
+++ b/gtk/PlatGTK.cxx
@@ -527,6 +527,22 @@ void SurfaceImpl::Release() {
 }
 
 bool SurfaceImpl::Initialised() {
+	if (inited && context) {
+		if (cairo_status(context) == CAIRO_STATUS_SUCCESS) {
+			// Even when status is success, the target surface may have been
+			// finished whch may cause an assertion to fail crashing the application.
+			// The cairo_surface_has_show_text_glyphs call checks the finished flag
+			// and when set, sets the status to CAIRO_STATUS_SURFACE_FINISHED
+			// which leads to warning messages instead of crashes.
+			// Performing the check in this method as it is called rarely and has no
+			// other side effects.
+			cairo_surface_t *psurfContext = cairo_get_target(context);
+			if (psurfContext) {
+				cairo_surface_has_show_text_glyphs(psurfContext);
+			}
+		}
+		return cairo_status(context) == CAIRO_STATUS_SUCCESS;
+	}
 	return inited;
 }
 
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 63d45158b..18eafa271 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -1830,6 +1830,13 @@ void Editor::PaintSelMargin(Surface *surfWindow, PRectangle &rc) {
 	RefreshStyleData();
 	RefreshPixMaps(surfWindow);
 
+	// On GTK+ with Ubuntu overlay scroll bars, the surface may have been finished
+	// at this point. The Initialised call checks for this case and sets the status
+	// to be bad which avoids crashes in following calls.
+	if (!surfWindow->Initialised()) {
+		return;
+	}
+
 	PRectangle rcMargin = GetClientRectangle();
 	Point ptOrigin = GetVisibleOriginInMain();
 	rcMargin.Move(0, -ptOrigin.y);