Barring a better answer, you can use this old trick if you like. It's been around since at least the XP days.
Open up Notepad and copy the following two lines of text to it:
set wShell=wscript.createobject("wscript.shell")
wShell.sendkeys "^{ESC}"
Save the file with a .vbs extension, for example StartButton.vbs
Create a shortcut to it in Object Dock.
Can't guarantee it'll work on Vista, but it worked on XP and continues to work on Win10.
