Description of problem:
system-config-display does not change monitor type if another monitor section 
is already present in xorg.conf.

Version-Release number of selected component (if applicable):
rhpxl-0.39-2 (FC6), rhpxl-0.43-1.fc7 (F7T2)


How reproducible:
by changing any of monitor related options like vrefresh, hsync, or monitor name

Steps to Reproduce:
1. Set inittial monitor section (assume that no monitor is already configured): 
system-config-display --set-hsync=31.5-86.0 --set-vsync=60-160 
2. try to change any of monitor options: system-config-display -o /tmp/
xorg.conf --set-hsync=31.5-60.0
3. see the difference: diff -u /etc/xorg.conf /tmp/xorg.conf|grep HorizSync
  
Actual results:
no differences found, i.e. second step failed

Expected results:
-        HorizSync    31.5 - 86.0
+        HorizSync    31.5 - 60.0


Additional info:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=176592 - seems to be 
duplicate
Actual bug is missing monitor related code in merge_into() routine from 
xhwstate.py (rhpxl package). See the attached patch that fixed issue for me.