Create context menu items for .bmp, .gif, .jpg

[sshrum]

I've been able to create context menu items for all files: "*" but I want to only show my context menus options for the file types my app supports.

This is what I have that works for *all* files using '*':

for $i = 1 to $iEnabledMonitors
    regwrite("HKCR\*\Shell\" & $sAppName & " " & $i,"", "REG_SZ", "Set as display " & $i & " background...")
    regwrite("HKCR\*\Shell\" & $sAppName & " " & $i & "\command","", "REG_SZ", @ScriptFullPath & " " & $i & "=%1")
next

I've tried putting in '.bmp' in place of '*' but the context menu doesn't display when I right click on .bmp files.

What am I doing wrong?

TIA