Gimp

These are silent installer entries for GIMP, GIMP-Help and GTK (available from http://gimp-win.sourceforge.net/stable.html):

NOTE: /SILENT Shows progress, /VERYSILENT is truely SILENT and has no dialogue boxes at all (running the gimp .exe with /? reveals all the switches).

GIMP

<package
  id="gimp"
  name="GNU Image Manipulation Program (GIMP)"
  revision="2440"
  reboot="false"
  priority="10">

  <check type="uninstall" condition="exists" path="GIMP 2.4.4"/>

  <install cmd='"%SOFTWARE%\gimp\gimp-2.4.4-i686-setup.exe" /VERYSILENT /NORESTART /DIR="%PROGRAMFILES%\GIMP"'/>

</package>

GIMP-Help

<package
  id="gimphelp"
  name="The Gimp help files"
  revision="0"
  reboot="false"
  priority="20">
    
  <check type="file" condition="exists" path="%PROGRAMFILES%\GIMP\share\gimp\2.0\help\images\callouts\1.png"/>

  <install cmd="%SOFTWARE%\gimp\gimp-help-2-0.9-setup.exe  SP- /VERYSILENT /NORESTART  /DIR=%PROGRAMFILES%\GIMP"/>

</package>

GIMP-Help doesn't create an Add/Remove programs entry.

The above remove command will work when any spoken language help files are installed.

GTK

<package
  id="gtk"
  name="GTK"
  revision="0"
  reboot="false"
  priority="0">

  <check type="file" condition="exists" path="%COMMONPROGRAMFILES%\GTK\2.0\bin\libgtk-win32-2.0-0.dll"/>
  
  <install cmd="%SOFTWARE%\gimp\gtk+-2.6.9-setup.exe SP- /SILENT /NORESTART"/>

  <remove cmd='"%CommonProgramFiles%"\GTK\2.0\unins000.exe" /SILENT'/>

</package>

Note that the check condition here relies on a version-specific file which could change, libgtk-win32-2.0.0.dll.

Package for newer gtk-2.10:

<package
  id="gtk"
  name="gtk+ 2.10.11"
  revision="1"
  reboot="false"
  priority="0">

  <check type="uninstall" condition="exists" path="GTK+ 2.10.11 runtime environment"/>

  <install cmd='%SOFTWARE%\gimp\gtk+-2.10.11-setup.exe SP- /SILENT /NORESTART'/>

  <remove cmd='"%CommonProgramFiles%"\GTK\2.0\setup\unins000.exe" /SILENT'/>

</package>

See also a silent installer and uninstaller for GTK2_runtime.