I have a taskbar button that points to 'FirefoxPortable.exe'. After clicking it the second button shows up, since the second process 'firefox.exe' is opened.
To solve that problem, I used the mkshortcut tool. I made a shortcut to 'FirefoxPortable.exe', but with AppId which is the same as the one from 'firefox.exe' (the whole process is described here). Since the Windows taskbar uses AppId to determine how to group buttons, it works perfectly and the second button doesn't appear.
However, I can't use the same solution for the DisplayFusion taskbar, since it doesn't accept shortcuts. I tried to programmatically change the firefox.exe AppId, which again worked with the Windows taskbar, but on the DisplayFusion taskbar the second button still appears. What does the DisplayFusion taskbar use for grouping? A path?
The DisplayFusion taskbar should be using the AppID as well, but it only caches the AppID if you pin the button via the right-click menu. Did you add the shortcut to the taskbar using the Taskbar Shortcuts window, or via a right-click on the button?
