I remember reading somewhere that Explorer splits application titles with dashes.
For example Mozilla Thunderbird uses this schema for an application title:
Inbox - user@example.org - Mozilla Thunderbird
Also applications like Microsoft Word and many others use a similar Schema:
SomeDocument - Microsoft Word
When Windows 7 was first introduced I remember that we had to modify our application to conform to this schema in order for the new TaskBar to correctly group the application windows into TaskBar buttons.
I am debugging a problem related to this, but I can't seem to find any official documentation on this.
Edit: I found some documentation on the recommended title bar text here: https://learn.microsoft.com/en-us/windows/win32/uxguide/text-ui#title-bar-text
Top-level, document-centric program windows: Use a "document name program name" format. Document names are displayed first to give a document-centric feel.
How does Explorer handle the appliation title / window titles with regards to the TaskBar buttons?