I have a brand new iMac running High Sierra 10.13.4. I have installed Minecraft 1.12.2 and Forge installed from forge-1.12.2-14.23.2.2654-installer.jar downloaded yesterday. When I launch Minecraft in fullscreen mode, everything looks normal. When I launch Minecraft with Forge in windowed mode, everything looks normal. When I launch Minecraft with Forge in fullscreen mode, I see this: (my pointer is over where the Quit Game button would normally be in fullscreen)

 

When I go into a world, the black part of the screen goes white, but the game is still just in the lower left corner and the mouse location is offset.

 

I searched for this issue and found some old recommendations to modify splash.properties which doesn't exist and add -Dforge.forceNoStencil=true to the JVM options which had no noticeable effect. I have tried removing, redownloading forge, and reinstalling. I have tried deleting the entire minecraft folder and reinstalling everything.

 

When I choose the launch option without Forge, everything is still normal. This only happens when I launch with Forge.

 

forge-1.12.2-14.23.2.2654-installer.jar.log

debug.log from minecraft/logs

latest.log from minecraft/logs

 

I have the same problem.  I can reproduce this on both the oldest and newest versions of Forge (1.12.2-14.23.0.2486 and 1.12.2-14.23.5.2768).  Disabling the splash screen (suggested for the same problem on 1.7) did not fix it.

 

However, I was able to work around the problem by, instead of having minecraft switch to fullscreen mode, click the Mac standard green circle in the upper left corner of the minecraft window.  This put minecraft into full-screen mode with working graphics.  I can then exit fullscreen by pressing the key I assigned to toggle fullscreen mode twice (the first stays in fullscreen but reduces the graphics to 1/4 of the screen, the 2nd restores non-fullscreen mode with working graphics).

 

So the work-around is mildly annoying but working well enough for me.  Hope it helps you.

 

Tye

Oh, disabling the splash screen actually does fix this problem.  I originally only found minecraft/config/splash.properties and changing it there did not help, but I now see I have a minecraft/1.12/config/splash.properties (1.12 is the game data directory I created for all 1.12 versions) and changing "enabled=true" to enabled=false" there fixed fullscreen graphics.

On 2/8/2019 at 9:37 PM, Tye said:

Oh, disabling the splash screen actually does fix this problem.  I originally only found minecraft/config/splash.properties and changing it there did not help, but I now see I have a minecraft/1.12/config/splash.properties (1.12 is the game data directory I created for all 1.12 versions) and changing "enabled=true" to enabled=false" there fixed fullscreen graphics.

On 2/8/2019 at 9:37 PM, Tye said:

i have a mac but i want to know how to edit the file

 

 

Yo im havin the same problem and i dont really understand what do do. Part of me thinks its because some leftover files from fancymenu is there and im thinking it could also be the ESSENTIALS mod.

 

Info:

computer: mac

MacOS version: 13.3.1 (a) (22E772610a) (Ventura)

Graphics card: Intel Iris Plus Graphics 640 1536 MB

and thats basically all the mac info i could get. (p.s i dont use optifine cause its buggy so)

nvm i fixed it it was the pre loading screen mod i had.