In GNOME bug 140362, someone requests the ability to maximise one side of a window to the edge of the screen by double-clicking the frame. Thomas provides a patch, there is some discussion, and the reporter realises that Metacity already does most of what is wanted through the ability to resize in one direction only when Shift is held down.
Your chronicler believes that this bug may be fairly closed since the reporter feels happy about the existing system. If anyone would like to make a case for double-clicking the frame having this effect, now’s your time to speak out.
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