Convert to Frames, Number of Frames increase

[tinkerer-red]

Is your feature request related to a problem?

Attempting to add emoji support to Scribble and ran into one of the biggest hurtles thus far, the inability to raise the frame count past 999

Describe the solution you'd like

it's obvious 999 is an arbitrary limit, if there must be a limit for technical reasons it would be nice if this value was right on the edge of that limit. However if it's not implicitly needed to be restricted it would be nice to be able to have another digit or two in this value if it's just a UI element issue.

Describe alternatives you've considered

Considering Collage. Or much worse off, adding them manually into the files.

Additional context

Obviously importing 2k unique sprites is not ideal.