Thanks a lot.
By creating mywechsel.ini and scripting as below, I was successfully able to excluding the app from lists of any previews in Dexpot.

"[Exe]
AIMP3.exe=ignore"

If the application is supposed to be visible on all desktops anyway, you can exclude it by setting it to "ignore" in the mywechsel.ini: [FAQ] What is the mywechsel.ini file capable of?

Let me know if you need any more help with this.

Assigning certain applications on every desktop is very usable, however those assigned applications are annoying because they will appear multiply on Window catalog.
For my instance, I assign AIMP3 on every desktop, but I don't want to see this on Window catalog because I can call this whenever I want from my hotkey.
That's why I want the Dexpot setting to exclude certain application that users do not want to see that on the preview.
I searched through the forum about this exclusion, however all I could find was only about monitor exclusion.