When it comes to exporting to PowerPoint I suppose it has a predefined size for the slides, which means that if my presentation in gamma has a size, when I want to export it to pptx it is cropped and it looks weird or there are parts left out, my recommendation is that they add some type of preview with a frame the size of the pptx slide so that the user can make sure that everything will be in the margins and he will not have to be exporting again and again to see the changes he is making with the size of pptx
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