Make it look more like the mockups. In order to do that we stop using PopupMenu and friends as it doesn't really buy us anything and just makes it more cumbersome to add the style classes we need. https://bugzilla.gnome.org/show_bug.cgi?id=691902
This is an implementation of the org.freedesktop.IBus.Panel API which shows a shell style popup (BoxPointer) when using an IBus input method. Based on code from the ibus-gjs project[1]. [1] https://github.com/fujiwarat/ibus-gjs https://bugzilla.gnome.org/show_bug.cgi?id=641531