thanks for reply but i didn't mean that what you replied. i want to use these three button in design time but what you say is just belong to something happening with form in runtime.
you can think of my problem as :- if you want to maximize the form in design time(not in run time) so you have to scale the form width of height using mouse dragging(i.e. can't maximize directly), so any ideas to activate these three buttons in design time.
You have a couple of options. 1 - When you click on the form, on the right edge and bottom edge you will see little white squares these are for changing the size by dragging the mouse cursor. You aren't restricted to the visible area of the IDE. You can drag it to the full size of the screen. Scroll bars will automatically appear so you can change which part of the form is visible.
2 - With AutoSize set to False, use the Size property to manually set the form to a specific size.