[SeS] I hereby would like to present a little wrapper to toy around with the Windows desktop properties. This gadget provides a way to perform the following two tasks, by means of the ffidl package and thus DLL-calls:
  1. hide all icons from desktop
  2. hide taskbar and Windows Start button

I can think of various reasons in terms of possible use cases:
  1. record a video of an application, with focus only on the GUI and desktop background wallpaper only
  2. provide a way of personalization of the desktop dynamically by a tcl/tk GUI, on demand

In fact, the upcoming beta version of [tG²] already has implemented this, including the method to change the background wallpaper too, also with DLL calls...
NOTE: The script is tested on a Win7 OS only...


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# ------------------------------------------------------------------------
# Part of ffidl_1.tcl for tG² - Generic BSD License is applicable, just in case:
# THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS 
# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL ROGER E CRITCHLOW 
# JR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF 
# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
# Copyright (C) 2009-2014 by Sedat Serper,
# ------------------------------------------------------------------------
package require Ffidl 0.6

ffidl::callout dll_ShowWindow {int int} int               [ffidl::symbol user32.dll ShowWindow]
ffidl::callout dll_IsWindowVisible  {int} int             [ffidl::symbol user32.dll IsWindowVisible]
ffidl::callout dll_FindWindowTitle {int pointer-utf8} int [ffidl::symbol user32.dll FindWindowA]
ffidl::callout dll_ShowWindow {int int} int               [ffidl::symbol user32.dll ShowWindow]
ffidl::callout dll_FindWindowByClass {pointer-utf8 pointer-utf8} int [ffidl::symbol user32.dll FindWindowA]

# ------------------------------------------------------------------------
# Purpose         : retrieve the HWND of an external Windows program
# Usage example        : getHwnd [wm title .]
# ------------------------------------------------------------------------
proc getHwnd {windowname} {return [dll_FindWindowTitle 0 $windowname]}

# ------------------------------------------------------------------------
# Purpose : toggles the visibility of the Desktop icons 
# ------------------------------------------------------------------------
proc toggleDesktopIcons {{mode toggle}} {
  set hWnd  [getHwnd "Program Manager"]
  set isVis [dll_IsWindowVisible $hWnd]
  switch $mode {
   "toggle" {if {$isVis} {dll_ShowWindow $hWnd 0} {dll_ShowWindow $hWnd 4}}
   "hide"   {dll_ShowWindow $hWnd 0}
   "show"   {dll_ShowWindow $hWnd 4}
  }
}

# ------------------------------------------------------------------------
# from generic_1.tcl tG2 wrapper 
# ------------------------------------------------------------------------
proc isInteger {theString} {
  string is integer -strict $theString
}

# ------------------------------------------------------------------------
# Purpose : toggels various attributes of the Desktop 
# ------------------------------------------------------------------------
proc toggleDesktop... {mode value} {
  switch $mode {
   "icons" {
     if {[isInteger $value]} {if {$value} {set value show} {set value hide}}
     toggleDesktopIcons $value
   }
   "taskbar"    {
     if {![isInteger $value]} {if {$value=="hide"} {set value 0} {set value 1}}
     dll_ShowWindow [dll_FindWindowByClass "Shell_TrayWnd" ""] $value
     dll_ShowWindow [dll_FindWindowByClass "Button" "Start"] $value
   }
   "all" {
     toggleDesktop... "icons"     $value 
     toggleDesktop... "taskbar"   $value 
   }
  }
}

# test with a Wish.exe session
toggleDesktop... all hide
tk_messageBox -message "What?! get back my icons and taskbar!"
toggleDesktop... all show

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