Hi Moshi,
Unable to locate the attachment which presumably shows the problem...
If you have tab pages (and they are user objects) define a new event for each and map to pbm_size. Then code each appropriately depending on what controls are on the page:
dw_1.resize ( newwidth - dw_1.x * 2, newheight - dw_1.y - dw_1.x)
(I usually use dw_1.x as the margin. That's why I subtract it from the height)
The overall tab is the same thing:
tab_1.resize ( newwidth - tab_1.x * 2, newheight - tab_1.y - tab_1.x)
HTH
Lars