Hi!
So uh, yeah. I'll try to keep this short and as informative as possible.

Running the game on a Mac with WINESKIN, the popular wrapper made for PST (can't remember the name :P)
Vanilla game is running fine.
Modded with PST FIX is running fine.
Modded with PST FIX and Unfinished Business is running fine.
Modded with PST FIX, UB and Widescreen and UI mod is crashing when I try to equip some items which is annoying since I can't play the game because of that.

Any ideas of what could be causing that? It's obviously either Widescreen mod or the UI (GhostDog's mod) mod but uh yeah, it's causing me a headache right now because I'd really, really like to play this game with these two mods too, I just hope there's a way to make it work somehow.

I know it's either widescreen/UI mod since I've started installing the mods one by one and everything worked fine until I installed these last two mods, process of elimination if you will.

Any help would be greatly appreciated.
Thanks in advance and sorry for making yet another bug/crash thread :|

I don't have any specific directions, but a few suggestions / questions. First please check and tell what versions of widescreen and ui mod you are using. There were some fixes made (relevantly speaking) not so long ago. Also try to run "Test run" in Wineskin menu or by some other way get log files. Post them here in a hope we see something in there.

My experience is that PST works pretty well in Wine, so you might consider doing your own wrapper using Wineskin. Only thing you might need to do is run Winetricks "ddr=gdi" in case you experience flickering. Anyway, whether you make a new wrapper or use existing, please specify which you are using so we can test it too.

Okay, I'll post more in a bit after I re-install and update all of the Wineskin stuff etc :)
It's a bit weird because the game runs flawlessly up to the point of installing widescreen and UI mod.

Alright, here goes.

This wrapper - http://portingteam.com/files/file/7181-planescape-torment/
Wineskin/Winery - http://wineskin.urgesoftware.com/tiki-index.php?page=Downloads
Mods from here - http://www.controlcommandescape.com/reviews/planescape-torment-review/

These are all the links, just in case.
Following the installation instructions from here -http://www.controlcommandescape.com/reviews/planescape-torment-review/

Wrapper version Wineskin v2.6.0
Engine WS9Wine v1.7.18
GhostDog's UI mod v2.2
Planescape: Torment Ultimate WeiDU Fixpack v4.13
Planescape: Torment Tweak Pack v4.12
Planescape: Torment Unfinished Business v4.12
Widescreen Mod v3.05

If there's more you need just let me know.
@Edit
I'll post logs in a bit.

Log after crash

fixme:win:EnumDisplayDevicesW ((null),0,0x33a604,0x00000000), stub!
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:ddraw:ddraw_surface7_Flip Ignoring flags 0x1.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
fixme:d3d_surface:surface_cpu_blt Filter WINED3D_TEXF_LINEAR not supported in software blit.
wine: Unhandled page fault on read access to 0x00000018 at address 0x50c461 (thread 0029), starting debugger...

And more

WineskinX11: main(): argc=12
Waiting for startup parameters via Mach IPC.
WineskinX11: do_start_x11_server(): argc=12
Attempting to use pixel depth of 24
[801336.429] WineskinX11 starting:
[801336.429] X.Org X Server 1.13.0
[801336.429] Build Date: 20120921
[801336.429] _XSERVTransmkdir: ERROR: euid != 0,directory /tmp/.X11-unix will not be created.
[801336.432] Initializing built-in extension Generic Event Extension
[801336.432] Initializing built-in extension SHAPE
[801336.432] Initializing built-in extension MIT-SHM
[801336.432] Initializing built-in extension XInputExtension
[801336.432] Initializing built-in extension XTEST
[801336.432] Initializing built-in extension BIG-REQUESTS
[801336.432] Initializing built-in extension SYNC
[801336.432] Initializing built-in extension XKEYBOARD
[801336.432] Initializing built-in extension XC-MISC
[801336.432] Initializing built-in extension XINERAMA
[801336.432] Initializing built-in extension PseudoramiX
[801336.432] Initializing built-in extension XFIXES
[801336.432] Initializing built-in extension RENDER
[801336.433] Initializing built-in extension RANDR
[801336.433] Initializing built-in extension DAMAGE
[801336.433] Initializing built-in extension MIT-SCREEN-SAVER
[801336.433] Initializing built-in extension DOUBLE-BUFFER
[801336.433] Initializing built-in extension RECORD
[801336.433] Initializing built-in extension X-Resource
[801336.433] Initializing built-in extension XVideo
[801336.433] Initializing built-in extension XVideo-MotionCompensation
[801336.433] Initializing built-in extension GLX
[801336.434] x: 0, y: 0, w: 1920, h: 1058
[801336.451] (II) GLX: Initialized Core OpenGL GL provider for screen 0
[801336.632] noPseudoramiXExtension=0, pseudoramiXNumScreens=1
Engine Used: WS9Wine1.7.18

I did a similar installation using instructions here:http://www.controlcommandescape.com/reviews/planescape-torment-review . After launching the game, I noticed that the main menu flickers a bit and also the mouse is very sluggish and it disappears once in a while. In fact the mouse was so sluggish at 1920 x 1200 resolution that I couldn't play the game. So my initial optimism in the ease of getting this game running with Wine pretty easy is fading away bit :/

My installation was done using instructions here: http://thunderpeel2001.blogspot.fi/2009/01/planescape-torment-fully-modded.html and I back then used original 4-CD version that I had. I am sorry but I can't give you any advice. There is some discussion here also: http://www.gog.com/forum/planescape_torment/planescape_torment_mods_guide/page5 that says that maybe you should try to install the widescreen mod first without other mods:

"This is because the WeiDu installer for the current Widescreen mod, (currently v3.05) is a bit older. When you run the installer, it checks for other WeiDu mods already installed on the game and it doesn't like newer versions of Weidu. WeiDu is actually a mod installer package system developed for Infinity Engine games that keeps track of your installed mods to keep them compatible with each other. Overall, WeiDu is great, but it does have a couple of quirks, like the one you mentioned. This will likely not be a problem, as soon as the next version of Widescreen mod comes out. In the mean time, you can work around it, jut by making sure you temporarily move other WeiDu mods out of the folder (like the DirectDraw-Fix) and install the Widescreen mod before any other mods (which should be done anyway)."

Maybe that is worth of trying, I'll try to make a working bundle myself too, but I am a bit busy at the moment. Also it might be that the directdraw-fix mod is not needed on Wine, at least I didn't use it back then.

Hm, that's fine then.
I would try this... if it allowed me to install the widescreen mod first without any mods. For some reason I cannot install it without installing the Fix pack first which is odd.
I will try to do some more testing because I've noticed the game is not always crashing, it didn't crash last time after I started switching and equipping items back and forth but I didn't have the time to try to just play the game because it was like midnight already.
Thanks for your help though, appreciate it! Have a nice day! :)

Thanks for posting that link. It "mostly" worked for me. I have PST now running at 1280x800 on my MBP under 10.9. I did have issues with their instructions on how to change the target WINE exe and run each update. I found it far easier (being a primarily PC guy) to copy all the files into the app as explained then run the Wineskin Command Shell. this gave me the good old DOS window to install all the patches. The app opens at full res now, I'm at work so I can't confirm whether anything breaks deeper in. Now I may try BG1/2 next. I travel with my MBP and would rather not have to reboot into bootcamp just for a game or two.

Did you solve this issue? Because I experience the exact same thing. Random crashes when playing with items in the inventory.

I'm on a MacBook Air with OS X 10.11 (El Capitan)

Same problem here.
The game randomly crashes during gameplay. The crashes are so frequent that the game is pretty much unplayable even when using quick saves.

I followed the steps outlined in the official GOG Torment Mods Guide to install the widescreen mod.

For some reason the 2.0.0.9 version of PST is not compatible with the Widescreen mod.

System Details:
Mac OSX 10.10.5
4 GHz Intel Core i7
32 GB 1600 MHz DDR3
AMD Radeon R9 M295X 4096 MB