Force re-layout / textview resize bug

[Kasper Peeters <kasper peeters phi-sci com>]

I am trying to change the text size of a TextView by calling (at
runtime, while the widget is visible) 'override_font'. This works
in the sense that the font changes, but the size of the TextView remains
the same, so the text in it gets clipped if the new font is larger. Only
after I resize the window and hence force a re-layout, the widget takes
its correct size. This is probably a bug, but it seems like this
suggests a workaround:

Is there any way to force a widget re-layout without requiring the user
to resize the window? 'queue_draw' does not work. 

Version info: gtkmm 3.10.1, gtk 3.10.8 on Linux Mint 17.3.

Best,
Kasper