Add Course Presentation canvas option of 4:3
Most of my users will access the H5P content on smartphones. Most of the individual modules are nicely responsive in reducing to a narrower screen, but the Course Presentation canvas is actually slightly wider than the 16:9 widescreen format.
PowerPoint has two default canvas sizes -- Standard 4:3 and Wide 16:9. Allowing a 4:3 canvas size will make it easier to create slides in PowerPoint that I can import as Images, knowing that the text won't shrink too badly on a smartphone.
I suggest offering two standard size canvases (Standard and Wide), with a Custom size available in the future.
If there are reasons why some of the inserted objects require a wider canvas, then I suppose it would be best for them to be removed from the Standard Width option.