Alert dialogs sometimes come up initially painted incorrectly when using GTK 3. This may or may not be Ubuntu 14.04 specific.

To reproduce:

1. Run HelloAlert with GTK 3

java -Djdk.gtk.verbose=true -Djdk.gtk.version=3 -cp apps/toys/Hello/dist/Hello.jar hello.HelloAlert

2. press the space bar

BUG: Sometimes the dialog comes up with a copy of a portion of the buttons drawn below and slightly to the right of the actual buttons. It looks like the initial repaint might not have had the correct repaint bounds.

Moving the mouse into the Dialog window will cause it to be redrawn correctly.

3. If the bug doesn't happen the first time, then press ESC and then SPACE repeatedly until it happens. On my machine it happens about 1/2 the time.

I'll try to capture a screen shot.

This happens at least as far back as build 148, so not a regression. I don't know whether this also happens on Ubuntu 16.04.