Suppress default message for (save/)close event with BUI extension

Summary:

Looking for options to suppress default messages and replace it with my own.

Content (required):

Requirement:

if an unsent response thread is present and the workspace is closed. display a message to the user reminding him/her of the fact that there is an unsent message, offer them a chance to send the message or continue closing the workspace.

So far we have managed to display our custom popup but if other changes were made to the workspace then the system will show the deafult prompt for unsaved changed changes twice.

once before our custom message and once after it.