none, it happened randomly

When i was playing on the minecraft server play.wynncraft.com on verson 1.7.9 i randomly wasn't able to shift-click items in my inventory, i wasn't able to shift-click at all. and if i try to drag an item, i need to hold the click, not single clicking and it follows the mouse, no i need to keep 'holding' it.
I tried restarting,changing versions, even a diffrent mouse.
But nothing worked. and it appeared just random.

What can i do?