File transfer on built-in CEmu emulator pauses and gets stuck when leaving tab

[Sumde]

On project builder, uploading a file with the "TI File(s)" button seen here:

disables the options for pausing/resuming, resetting, uploading any other files or uploading any ROM files, until the file transfer is complete.

On the other hand, leaving the tab pauses the simulation, of which you have to click the resume button to resume the emulation again. Unfortunately, leaving the tab while the file transfers pauses the simulation, and disables the option to resume it, making the screen permanently frozen (until you refresh the tab), which looks like this:

As you can see in the above screenshot, you are not able to click the "Resume" button (as it is greyed out), which pretty much bricks the emulation until you refresh the page (which, can delete any progress or files you put on the emulator).

[adriweb]

Fixed in the private repo (e27713c7afbe154128cf7293f49acc535c2ba696).
Will publish the various recent commits including this one in the public repo (this one) soon.

[PB] avoid CEmu transfer deadlock on hidden-tab auto-pause.

Before this change, The PB's visibility handler could pause CEmu
while a file transfer was in progress. That left the transfer stuck,
kept emulator controls disabled, making it all appear frozen
until a full page reload.

Now, we:
- defer pause requests while a CEmu file transfer is active
- resume temporarily when needed so transfers can complete
- restore a pre-transfer paused state afterward
- only reapply a deferred visibility-triggered pause if the tab is
  still hidden when the transfer ends

[adriweb]

i'll keep the issue open until the commit here closes it, actually