lets say we have a textbox in a windows form, i would like to raise an event when mouse clicked out of the textbox area like clicking other controls or the form itself, any idea??

Capture the x and y point for text box and compare it on Mouse down event/Up with click point position to find out where exactly click happened. if click position is not in the range of text box position then raise your event. could be dirty way but will help you out.