Created attachment 51572 [details]
Screenshot after step 7.

Version:           4.0.0 (using KDE 4.5.1) 
OS:                Linux

When changing a color in the configuredialog and applying that change, only the middle piece (between before and after) is redrawn.

Reproducible: Always

Steps to Reproduce:
1. Start Konsole.
2. Create a directory and cd into it.
3. Create the empty file empty.cc
4. Create the file prov.cc with some content like this:
float calculate_something(float const a, float const b, float const c) {
   return
      calculate_something(1.7, calculate_something(8.9, 19.51, 33.0), a) +
      calculate_something(c, 18.8, calculate_something(7.5, b, a));
}
5. Execute "diff -u empty.cc prov.cc|kompare -".
6. Open the settings dialog and change the background color of added blocks.
7. Press Apply.

Actual Results:  
Only the middle part is redrawn (see attached screenshot).

Expected Results:  
Also the before and after parts are redrawn.

The change does take effect if font is also changed before Apply is pressed, or the configuredialog is closed (OK or Cancel).