Sylpheed

Sylpheed's notification window always pops up at bottom-right.

I use dual-display (left display0 and right display1) with Xinerama.

I decide to use display0 as main one and display1 as sub one.
I place Sylpheed at display0 and expect Sylpheed pops notification window up
at display0's bottom-right, but it pops up at display1's bottom-right (certainly "right").

I hope customizable notification window pop-up position
or it pops up at same display Sylpheed stays.