Hello, darpan:

You ask for some way to increase size of toolbuttons to 48x48 using Qt3. The answer is that it's not posible. The limit is 32x32 (see documentation for class QToolButton).

Everall solution, is to use pushbuttons instead of toolbuttons, then you can increase size to what ever you want, but just for the icons in the push button. The toolbuttons will keep there size (32x32 as an upper limit).

If you have to use 48x48, you have to use everall solution and change all your toolbuttons with pushbuttons. If your design admits a 32x32 limit, then you can use my solution, with no need to change toolbuttons with pushbuttons.

Hope this can help you.
Good luck.