Fix tiled backgrounds using height not width

Fixes issue 3712

Change-Id: I9f55ee2230c0083d14b25c9eda4da10109d57a0f
Reviewed-on: http://gerrit.dmdirc.com/801
Reviewed-by: Shane Mc Cormack <shane@dmdirc.com>
Automatic-Compile: Shane Mc Cormack <shane@dmdirc.com>

src/com/dmdirc/addons/ui_swing/UIUtilities.java

@@ -422,7 +422,7 @@ public final class UIUtilities {
     private static void paintTiledBackground(final Graphics2D g,
             final Rectangle bounds, final Image backgroundImage) {
         final int width = backgroundImage.getWidth(null);
-        final int height = backgroundImage.getWidth(null);
+        final int height = backgroundImage.getHeight(null);
 
         if (width <= 0 || height <= 0) {
             // ARG!