9.4 Insert empty gap
Static
Fixed size.
<text width-chars="40" height-request="120"><label>" "</label></text>
Dynamic
Align one button to the left, another to the right. Empty gap will fill the rest.
<hbox space-expand="false" space-fill="false"> <button yes></button> <hbox space-expand="true" space-fill="true"><text><label>" "</label></text></hbox> <button no></button> </hbox>
