This moves a fiddly little bit of logic used by a few UI
classes into a central location.
Also means that the paths dialog learns to expand the
first cell when it needs to (like the text variable
panel).
Found via `codespell -q 3 -S *.po,./thirdparty,./Documentation/changelogs -L aactual,acount,aline,alocation,alog,anormal,anumber,aother,apoints,aparent,aray,ba,busses,dout,einstance,leaded,modul,ontext,ot,overide,serie,te,,tesselate,tesselator,tht`
A note to developers, please do not set the minimum and/or size of bitmap
buttons. It causes bitmaps to get clipped using GTK on Linux. If the
bitmap button size is not acceptable, then supply an appropriately sized
bitmap rather than attempt to force the wxWidgets sizing mechanism to do
what you want. This almost always causes platform differences that do
not work well.