The PAW graphical window is corrupted when overlapped with another window.

On (UNIX) machines using X-window, the HIGZ package (and PAW) relies on the ``BackingStore'' facility provided by X-Window to update the content of the graphics window when it has been damaged by an other window put on top of it. Very often the X11 (X-Window) server start with the ``BackingStore'' activated by default. But some servers don't. In that case you should activate the ``BackingStore'' when you start your X11 server.

The way to activate the ``BackingStore'' depends on the type of machine you are using.

On X11 platforms:
- LINUX: It depends which daemon is in charge of putting up the login box on the X-Windows screen, and start the X-Window session at login time. It can be xdm, kdm (provided with the KDE environment) or gdm. If it is xdm or kdm the line starting the X server in the file /usr/lib/X11/xdm/Xservers should not contain the option -bs it should look something like:
```
 :0 local /usr/X11R6/bin/X +bs 
```
  If it is gdm the line starting the X server in the file /etc/X11/gdm/gdm.conf should contain the option +bs it could be something like:
```
 0=/usr/bin/X11/X +bs
 
```
  With some LINUX systems (for instance Suse Linux 7.2) the file .fvwm2rc should contains the line:
```
 Style  "*"  BackingStore
 
```
- XFree86 4.0.1: The Screen section of the file /etc/X11/XF86Config (or /etc/X11/XF86Config-4) should be something like:
```
 Section "Screen"
      .
      .
      .
    Option "backingstore"
      .
      .
      .
 EndSection
 
```
- SGI: In the file /var/X11/xdm/Xservers set the option -wm.
- IBM RS 6000: In the file /usr/lpp/X11/defaults/xserverrc declare: EXTENSIONS="-bs -su"
- An other way: Start the X server with option +bs. This can be done by adding the option in the .xserverrc file in user's home directory:
```
 #!/bin/sh
 HOST=`hostname`
 exec X +bs -bpp 32 -auth ${HOME}/.Xauthority
 
```
Note that once the necessary modifications have been done, the X server should be restart. Rebooting the machine may be necessary ...
On Windows 95, 98, 2000 and NT platforms:

Two possibilities:

You are running a native PC version of PAW. In that case X11 is not involved. HIGZ provides the possibility to restore the corrupted window using the "double buffering". If you use PAW you should include in your file pawlogon.kumac the command SET 2BUF 11

Your are running remotely a X11 version of PAW. In that case you should activate the 'backing store' option in your X11 emulator on PC. For example with Exceed you should proceed as follow:

Start --->
    More Applications
       ---> Exceed X-terminal
              ---> Exceed Applications
                      ---> Xconfig
                            ---> Performance

Activate the "Save Unders" option (this eliminates the need for the client to refresh the window when the menu is rolled back up).

Then select:

    Maximum Backing Store: Always (attempt to preserve the contents
                           of any window, whether it is mapped or not,
                           as long as it is displayed on the X server)
    Default Backing Store: When Mapped
    Minimum Backing Store: When Mapped
    Tune... ---> Run All (this runs automatically some tests)

Then start again your X11-session