that is paticle's problem...i have a skill button in main scene,the button's RQ is 3000, and it has a paticle FX which has a RQ 3001 to render front the button, but i have another window,when this window opened, it will cover the skill button while not cover the button's FX, so i must change this window's RQ to a higher num(7000) to cover the FX....
while this window contains a input field..so i come to the problem....