Created attachment 195938 [details] Presentation with 2 root master pages The current import generates for each slide layout its own master slide although the layout from PowerPoint could be represented by the slide layout in LibreOffice. The problem with the current approach is, that the information about the root master slide is lost. So changing e.g. the background in a master slide does not affect all associated slide layouts. And resaving to pptx generates a lot of master slides that do not exist in the original document. To examine the situation you can use the attached file. It has two root master slides in PowerPoint. The first one has four layouts, the second one three layouts. After opening in LibreOffice you have seven master slides instead of two. I know that PowerPoint allows "child master slide" with associated layout. That concept differs from the concept of ODF, that has the layout on the individual slides. That problem is tracked in bug 62332. The request here is this: If a "child master slide" differs from the root master slide only by layout in PowerPoint, then LibreOffice should use the ODF layout mechanism and do not create additional master slides.
Reproducible Version: 25.2.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: 85e4dc15d09dc3193870041b2814263971a27791 CPU threads: 16; OS: Windows 11 X86_64 (10.0 build 22631); UI render: Skia/Raster; VCL: win Locale: es-ES (es_ES); UI: en-US Calc: CL threaded