Not sure why this is so hard, but so many dialog boxes in Robot are not adjustable. It's dumb simple to do. Its a major usability issue as in the case of the load case / combination selection box, I can't see even half of the name of the load combo. Its really hard to tell which one I'm selecting.
Guessing these are in C++ using MFC library (just add WS_THICKFRAME):
IDD_DIALOG_DIALOG DIALOGEX 0, 0, 320, 201
STYLE WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME