stability release #3

Linux version of significant stability issue in the builder.

1) I had event_lock system which disabled swapbuffers() and renderi() for a while using a timeout, but sadly left glClear() calls to fill the opengl draw command queue. Once swapbuffers were reenabled, the gpu was running at 100% until linux kernel killed the opengl parts of the app => causing significant jamming issues for the builder tool.  Moving the mouse made the problem disappear. Keeping mouse still caused 100% gpu spikes. :)

This improves builder tool stability alot.