I really can't say something about this, I am unable to play the game windowed, it crashes every time. I don't think that my UI has anything to do with it your problem, it's probably coming from the Widescreen mod. Bigg mentions in the readme that there are problems with windowed mod for PST (although I can't exactly decipher what he means) :
maybe he actually means "can be forced" and "can't work".BG1 and PST cannot be forced to be windowed, but can work at all X by Y, with X >= 640 and Y >= 480.
I've checked game in full screen mode and problem still exists. While using only big's mod I can scroll screen in all direction but animated arrow it's "trapped" in small (640x480) box in upper left corner. In the same box game displays all information windows (inventory, character page etc). But "trapped" I mean that I can actually move cursor pointer all over screen (1280x768) but when cursor reach edge of the screen animated arrow is displayed in that small (640x480) box instead of edges of screen.
When you move mouse pointer to edge of the screen game change it to animated arrow and allow to scroll screen. I don't why but after installing your mod I can't get animated arrow (scrolling one) to appears on left and bottom edges of screen.
PST_error1.JPG 49.04K 417 downloads
If you look at above picture (I've take 4 screnshoots and merged them into one picture).
Figure 1 - shows animated arrow which allow me scroll screen
Figure 2,3,4 - shows mouse pointer while moving it to right edge of the screen. As you can see on figure 4 mouse pointer is behind edge of the screen, but it should change to animated arrow and start screen scrolling.
I'm not sure but I think that game have two sets of coordinates one for displaying area (this one is fine) and second for scrolling screen. There is something wrong with those coordinates in my exe file, so could you tell me where to look (what offsets) for coordinates of left and bottom edge of the screen used in screen scrolling.