WINAPI Polygons - I need help

I am currently in the middle of programming a game engine. I have attempted to use the CreatePolygonRgn and PtInRegion for doing boundary detetion and simulating z-order when I draw multiple images onto screen using BitBlt. As far I can tell the polygons are being created and I know all the points specififed are correct, but it never returns the correct value when I specify a point in the region to be tested. I would also like to know if all values are to be specified in TWIPS or Pixels. I am using TWIP vaules right now because I used Pixels to no avail. Any help would be appreciated.

Vince

I'm not sure about how to properly use PtInRegion as I've never worked with regions myself (I think I might now just for the hell of it), but as far as I know, graphical APIs always operate with pixels as the given measurement. Maybe there is an oddity in how it treats pixels on the edges or something. I know that for RECT structures, a point on the left or top edge is considered in the rect, but for the bottom and right edge it's not.

all api- calls from the gdi works with pixel not with twips