Unity: clarify Meta, ALCOM drag crash

content/docs/vrchat/unity.md

@@ -74,11 +74,11 @@ This can happen with Poiyomi. It's caused by case-sensitivity. You may need to e
 Unity may open undocked panel windows (such as color pickers and unitypackage import dialogs) partially offscreen.
 
 Some workarounds:
-- For KDE, hold the Meta key and click anywhere in the window to drag it back onscreen.
+- For KDE, hold the Meta (AKA Super, AKA WinKey) key and click anywhere in the window to drag it back onscreen.
 - Alt-Tab to the specific window, then press Meta-Right to snap the window to the right side of the screen.
 - For KDE, press ALT+F3 -> More Actions -> Move.
 
-### Drag-and-drop does not work
+### Can't drag-and-drop files from external programs
 
 Rather than using Assets -> Import New Asset or Import Package, it's normally possible to drag-and-drop a unitypackage or other asset from a file browser directly into Unity's Project pane, where it will be copied to the Assets folder.
 
@@ -92,6 +92,22 @@ As a workaround, launch your file browser in Xwayland mode. Unity will accept th
 WAYLAND_DISPLAY="" dolphin
 ```
 
+### When Unity is opened via ALCOM, it crashes when dragging a hierarchy object
+
+{{< hint info >}}
+
+**Note**: If you are on Nvidia, see the [Crashing frequently with Nvidia](#crashing-frequently-with-nvidia) section first.
+
+{{< /hint >}}
+
+An ALCOM-launched instance of Unity can crash after trying to drag-and-drop an item (within Unity, ie. not external programs).
+
+This will likely be fixed by ALCOM v0.1.14.
+
+https://github.com/vrc-get/vrc-get/issues/1346
+
+Analysis: ALCOM has a different environment than the rest of your system, mostly by virtue of being an AppImage. This means the Unity subprocess that it spawns will inherit its crummy vars. The one at fault here is likely `GDK_PIXBUF_MODULE_FILE`. Unfun fact: This causes several other problems too (such as GTK-themed menubars and context menus on a KDE system), but I'm not sure the cleanest way to unset those vars yet. A wrapper script around the Unity binary?
+
 ### VRCFury builds lock up the editor
 
 Maybe due to the windows offscreen issue mentioned above, when starting build or play mode, the VRCFury progress window may initially be invisible, or pop underneath, which gives the *appearance* that the build isn't doing anything and has locked up. Use the "Alt-tab to the specific window then Meta-Right" trick to get the VRCFury progress window to appear onscreen again. That window may also be solid black, but this doesn't necessarily mean the build has frozen.