No problem I opened 100 all at once so they are all listed then opened yet another

what you seem to have is a screen limitation of opening more files than Windows may be expecting to handle.
the limitation historically was 10 files becomes a workflow hurdle as then there are no easy ways to tag them on keyboard unless use an accelerator key

To read the active tabs use Ctrl+K@ (you could try to add an icon or shortcut to open listing

Yes im using keyboard shortcuts but I can't open more file unless I close some first. How to change this kind of limitation ?
cheers.

If your windows session is restricting file handles so they need release before reuse that is outside SumatraPDFs control the tab line and file opening I showed had no problems handling 101 files but I did not bother to go higher as eventually I might have issues but you would need to use system diagnostic to see why your system is potentially limited in that fashion, since personally don't see a problem but the developer might ? are you sure if you select 36 files you cannot open all at once ?

what are you doing that you need more than 35 documents open at once?

haha I know... but if files are opened don't have to remember what to open on another day and so on... everything is saved. Helpful.