If the window is resized it was possible that xpos pointed outside the
visualization texture. By rearranging the overflow check we make sure this (and
a crash) does not happen.
We also don't have to use xleft for start position, as that is 0 anyways, and
if we ever want to take into account xleft then the texture should be
positioned accordingly when rendering.
Signed-off-by: Marton Balint <cus@passwd.hu>
(cherry picked from commit 573f05a7533cd9aed3ed895b4fa4ad8fcba4e56a)
4bbcaf7559