problem in mouse event

hi,

i rendered the some picture by polygons in qglwidget.
i used belo functions

initializegl();
paintgl();
resizegl();

in side paintgl() just i cler buffers and call draw() function, in which i have algorithm for rendering

for zooming and panning i have written code inside

wheelevent()
mousemove event()

now problem is when i move the mouse or moving wheel instantly it is not updating the glwidget.

but when i resize window it is updating. the same thing is happening even for push buttons.in this case once after clicking the pushbuttons if click mouse on screen it is updating

can anyone help me in this regard so that i'll be thankful to you and i can move furher in my project

thanks and regards
bhogasena reddy