I'd help, but I managed to type 'NoShiftMoveMap.delete();' in the console to see what happens and it stopped me from using tools or the paint cans in Blockland.
So I restarted Blockland and the problem remains.
After a bit of playing around, I noticed..
If you're typing or anything that has your mouse not moving your player's view, and you get disconnected from the server, something weird happens.
It fixed my problem too.
But the problem made me not be able to use the mouse to click on chat links, and it didn't fix it, but it fixed the other stuff. Infact, I can't click on links even with a GUI up. I don't know if you could before, but still.
I'd say to check IGSO for some stuff.
Edit: Added stuff.