I want to open these files with the panels collapsed; I want a clean view to view theses. And in general, to keep the panel collapsed, If I want to edit or anything I can open the full panel. I recently got an Issue with this. And I shared my screen with support, with the right configuration in the preferences, for regaular files like a Presentation or a Document it would open with the panels collapsed, but for documents like Plans created with CAD files it would keep opening either the thumbnails or layers panels, and we figured out that for certain files (PDF created from CAD software) keep opening the right panel, because they have it in their properties, like each files has its own property to open the page and the panels, so in order to keep this file from opening the panel you have to change this property manually and save it, so the next time you open it wont open the panels. It's so annoying