[meld/meld-3-16] diffmap: Avoid cairo surface creation for negative sizes (bgo#773985)

[Kai Willadsen <kaiw src gnome org>]

commit 269fb7bbb81859dc4f9ace82f2084f45718ef84c
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Tue Nov 8 07:35:19 2016 +1000

    diffmap: Avoid cairo surface creation for negative sizes (bgo#773985)
    
    This can occur on initial allocations when we don't have a real
    allocation ourselves yet, and the theme includes scroll arrows,
    resulting in us trying to create a cairo surface with a negative
    height.

 meld/diffmap.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/meld/diffmap.py b/meld/diffmap.py
index bb44a76..232cf4a 100644
--- a/meld/diffmap.py
+++ b/meld/diffmap.py
@@ -123,7 +123,7 @@ class DiffMap(Gtk.DrawingArea):
 
         # Hack to work around a cairo bug when calling create_similar
         # https://bugs.freedesktop.org/show_bug.cgi?id=60519
-        if not (width and height):
+        if not (width > 0 and height > 0):
             return
 
         context.translate(0, y_start)