Qt, Gtk, Tk, wxWidgets, Delphi (whatever the open source one is). All have pros and cons depending on your needs but you should be able to throw something prett

Qt, Gtk, Tk, wxWidgets, Delphi (whatever the open source one is). All have pros and cons depending on your needs but you should be able to throw something pretty serviceable together pretty quickly. The biggest catch for most is the reliance on c/c++, but if you want to be lean on memory then you probably want this anyway. Some of these are heavyweight, others are just wrappers for the native libraries. If this is a dev tool I wouldn't rule out a curses based TUI app either.