If a button is a default button and has a relief, its background and frame will be drawn twice (see moz_gtk_button_paint in gtk3drawing.c, note that case where state->isDefault and relief == GTK_RELIEF_NORMAL). This appears to be unintended, and is not done by upstream GTK's gtk_button_draw.
This should more accurately follow the upstream GTK implementation, and make default buttons look correct. Thanks!
Attachment #8639558 - Flags: review?(karlt)
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