add an option "flat_button" which acts in a similar way to the same option in xfce-panel's tasklist plugin

[jpleau]

The single reason why I needed this was I was trying to theme the button that whiskermenu adds to the panel.

I was trying to add a transparent png with the pixmap engine, and thus needed to theme "state = NORMAL", however it was hard-coded as GTK_RELIEF_NONE. Rather than just changing the value manually in the code, I added a single checkbox next to the Display options for the icon.

Checking it sets the button's relief to GTK_RELIEF_NONE (by default, and that's the current setting)
Unchecking it sets the button's relief to GTK_RELIEF_NORMAL

[gottcode]

I'm sorry, I will not be merging this. However, I have added a widget name for the panel button itself ("whiskermenu-button") with commit 1caf5fb; you should now be able to theme the git verion's panel button however you like.

[jpleau]

This option does not allow me to theme the button, as it does not draw my background (with pixmap engine) when the button's state is NORMAL (because of GTK_RELIEF_NONE)

I'm fine with you not merging since it's not an option that a lot of people would use, thanks for the quick reply.