ALT+ROTATE seems to be broken under Linux on v6.2.3 (tested on two different Linux machines running Ubuntu 14.04 - one 32bit and one 64bit - one was a fresh install just made only to check if this bug appeared on another machine too.)

Pressing the ALT modifier with rotate (either Q/E or left-mouse-button + mouse wheel) generally makes the selected object disappear down to the bottom left corner of the screen temporarily and doesn't rotate the object.

Odd bug!


PS After much experimenting, I discovered that pressing SHIFT before ALT, then releasing SHIFT whilst still pressing ALT, hackily works around this issue and allows the rotation in the other axis - proving the function itself works, it's just a bug in the modifier-keys handling code.