unity.md: Add two new troubleshooting sections

content/docs/vrchat/unity.md

@@ -74,6 +74,7 @@ Unity may open undocked panel windows (such as color pickers and unitypackage im
 
 Some workarounds:
 - For KDE, hold the Meta 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
@@ -89,3 +90,17 @@ As a workaround, launch your file browser in Xwayland mode. Unity will accept th
 ```
 WAYLAND_DISPLAY="" dolphin
 ```
+
+### 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.
+
+### Moving file failed
+
+A dialog may appear upon trying to build an avatar, where none of the buttons are helpful:
+
+> Moving Temp/unitystream.unity3d to /tmp/DefaultCompany/Some Avatar Project/prefab-id-v1\_avtr\_00000000-0000-0000-0000-000000000000_0000000000.prefab.unity3d:
+>
+> Force Quit | Try Again | Cancel
+
+This seems to happen consistently if the projects are stored on an EXFAT partition. Consider using another filesystem, such as NTFS if you still need projects accessible under both Windows and Linux.