event dropping on x11

There could be a case of Qt dropping input events on X11 platform.
Running native version on Linux and overloading it to a point where there is a lag in painting (e.g. by using a large airbrush) will cause the painting to become "blocky" (there will be long lines visible where should be much greater granularity). Running windows version using wine produces different results - much smoother painting regardless of the lag.
This is yet to be confirmed - debugging builds need to be built and their output compared. Luckly, there is a "xnee" tool (http://www.sandklef.com/xnee/) that provides utilities to record and replay X events (user actions).