Fix flickering Ubuntu-mono-dark keyboard icon in Gnome Shell

I’ve always been a big fan of Gnome Shell since its release in 2011. However, one thing that always bothered me was the Gnome icon set, specifically the folder images. In contrast to the rest of Gnome Shell, which looks very clean and modern, the folder icons of the default Gnome icon theme look a lot like 1990 :-) I therefore prefer sticking with the default Ubuntu icon theme, or rather Ubuntu-mono-dark to be more precise, since its monochrome tray icons work great with the rest of Gnome Shell. However, since the release of Precise Pangolin, which ships with Gnome 3.4, I’ve noticed a problem with the keyboard icon, which appears next to the user menu in the upper right corner when you use input methods like iBus. Right after you log on, the keyboard icon starts jumping around, changing size every few milliseconds. This usually stops at some point, but still, it’s a major annoyance and enough to put a few people off using the theme I imagine… [...]