You might find something useful
Here. Using the "Search" feature on that page, enter "mouse" as the keyword, set the 1st dropdown to "descriptions", and from the sub-category dropdown, select "Dos: Pascal" then execute your search. A list of .zip files which are mouse-related Pascal applications should be returned; dunno if anything there is what you're looking for, but the documentation accompanying some of the files could point you in the right direction.