The KeyEventArgs class in WinForms implements the Boolean SuppressKeyPress property. KeyEventArgs provides data for the KeyDown and KeyUp events. The SuppressKeyPress property can be set to True in a KeyDown event handler to suppress the subsequent KeyPress event - this purpose is clear. But is there any effect of setting SuppressKeyPress to True in event handlers of the KeyUp event?
I totally agree with all commenters that SuppressKeyPress is absolutely useless in KeyUp. As @Jimi explained, this field appears in KeyUp only because of the specific internal architecture of the Control class.