Theme isn't finalized after reloading
When reloading a theme,
It's quite easy to debug, just adding a print statement in
g_print("FINALIZING THEME %p\n",theme);), then from looking-glass just run
imports.ui.main.loadTheme() (as it would happen when specific signals are emitted) and this won't ever happen until all the widgets theme nodes are updated, and this could never happen as some unmapped widgets don't unset the previously used theme.