How to resize thumbnail previews in startpage?

[7eopard]

I've read advance setting's docs, but failed to did it.

When a pdf or epub file is opened and shown in startpage, it would be way better if theirs' preview is "complete", that is, in protrait view. Thinking I'm looking for a way to do so.

[GitHubRulesOK]

It is a fixed ratio ? 212 x 150? so only way to fool it is change the files inbuilt cover to landscape/upper half of portrait, or edit the SumatraPDF sources

[7eopard]

Now some preview are stretched, some titles are hidden. Sad.

[GitHubRulesOK]

they should not be "stretched" it is 212 x 150 depending on source scale
Agreed they can be less useful when its a folder icon or the title is at bottom of page

So it is possible to put your own image in place of the stored one HOWEVER it may be replaced by another copy of the old one later so you need to force file / folder to read only (not a good idea)