I happens that I get PPT documents that contain literally HUNDREDS of master slides. There is no good reason for this other than people do not know what they do. In order to clean those up it is super tedious to select each Master slide individually and delete the superfluous master slides one by one. Please allow multiple selection in the Master Slides Browser in Impress to delete multiple Master Slides in one step.
Created attachment 196210 [details] example of a Master Slide browser view Note the scrollbar!
*** This bug has been marked as a duplicate of bug 159860 ***