@b4n , thanks, looks better: 
However, I don't understand why you see a "missing image" image under GTK3.
Maybe problem [here](https://github.com/geany/geany-plugins/blob/master/geanylua/glspi_dlg.c#L14): `GTK_MESSAGE_OTHER` (without icon) replaced by `GTK_MESSAGE_INFO` (with icon)?