You need at least Internet Explorer 10, or you may want to give Firefox or Chrome a try.
I drew this on the web! does it make a difference?
The desktop tools have better performance, but the bug occured in both, web and desktop app.
Generally I would recommend to use the Desktop tools, especially if you are on a Mac. Flash support in the browser gets more and more worse on a Mac
And on the Mac you have pressure support for Wacom tablets (Desktop tools only).
there was a bug in queekypaint when merging layers.
this is fixed now, sorry for any inconvenience ..
Do you work with Web- or Desktop-App?