Thank gapan,
thank you for the good job with Salix.

If i start qemu from terminal with '-vga vmware' I get this messages:
vmsvga_value_read: Bad register 2b
vmsvga_value_read: Bad register 2c
with '-vga std' no messages from terminal.

I use qemu in sdl full screen mode, and frequently I switch between sdl
window and host's desktop (Ctrl+Alt+f, or ...

Now i am checking qemu 2.4.0 from sourcery with sdl 1.15.
I have no messages from terminal now, two lines with bad register value with previous installation.
I will be more precise when i get back on another machine with the same problem.

Last test uses qemu-2.4.1 from slackbuilds.org.
qemu.SlackBuild was modified to use 'kvm' group, LIBUSB="yes" and
to enable vde.

Using qemu 2.0 or greater with sdl 1.2.15, the sdl window closes suddenly.
With sdl 1.2.14 seem all right.