A weird window decoration problem occurs with Firefox when launched in a maximized state with Title bar disabled. It opens fine, but once resized it has this odd extra decoration on the window (see the picture). The bug doesn't go away when maximized again and occurs for all new windows launched in a maximized state.
When Firefox operates with Title bar enabled, it behaves as expected.
I have Global Menu and the WIndow Picker applet in the top panel. The Global Menu applet crashes often when I switch applications quickly. The window decoration problem occurs on Marco with or without Compton, as well as on Compiz.