Added scroll past end behavior (overscroll)

[FastestMolasses]

Description

Added optional functionality to allow the user to scroll past the end of the document, like in Xcode or VSCode.

Related Issues

Closes #76

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots

This is showing an extra 50% of the available screen. It will properly update when resizing the window as well.

Screen.Recording.2025-03-30.at.4.58.39.PM.mov

[thecoolwinter]

This works well, but I should mention we already implement overscroll in CodeEditSourceEditor.

Personally, I don't think this package is the place for it. In my mind this TextView class has to be managed by some container view, which should handle things like overscroll. In CodeEdit's case, that's the scroll view in CESE. I hate to waste your time on this though!

[FastestMolasses]

The implementation in CodeEditSourceEditor is a little buggy (jumps around sometimes) and it doesn't allow the user to click in the extended area to set the cursor to the end of the file. Is there a known fix for this? If so I can implement it.

[tom-ludwig]

I spoke with Austin about this the other day, and if this gets merged, I’d like to have a direct implementation in Settings where the user can choose the overflow amount.
Everything else looks fine to me.

[FastestMolasses]

I spoke with Austin about this the other day, and if this gets merged, I’d like to have a direct implementation in Settings where the user can choose the overflow amount. Everything else looks fine to me.

Awesome, I do have this PR ready to go that edits the overflow amount in the settings menu: CodeEditApp/CodeEdit#2010

It can be reviewed and merged now, but it will use the current implementation. Depends on what we want to do here, I do find the current implementation to be a bit buggy though.

[austincondiff]

Looks good!