Change behavior of PageUp and PageDown keys

[JFormDesigner]

The behavior of the PageUp and PageDown keys in RichTextFX is IMO very unusual compared to other editors (Eclipse, IntelliJ IDEA, etc).

Let's say the text is 1000 lines long and there are 50 lines visible.

Pressing PageDown key in RichTextFX moves the caret down 50 lines and then scrolls the caret into the visible area. In case the caret was at the top, RichTextFx scrolls only one line down. The caret is then at the bottom of the visible area.

In other editors, the text always scrolls 50 lines down and the caret is also moved 50 lines down.

Would it be possible to change this in RichTextFX?

[JordanMartinez]

Just to be clear, you're saying the new behavior should move viewport so that it goes from displaying lines B to D to displaying lines E to G, correct?

----------- < top of document
|A
|======= < top of viewport
|B       < first line in viewport
|C
|D       < last line in viewport
|======= < Bottom of viewport
|E
|F
|G
|------------- < bottom of document

I've wondered about this myself. I'm ok with changing it. If people want to change it back, they can override the default behavior to what it was before.

[JFormDesigner]

Just to be clear, you're saying the new behavior should move viewport so that it goes from displaying lines B to D to displaying lines E to G, correct?

Yes, exactly.

[JordanMartinez]

@JFormDesigner mind submitting a PR for this? Shouldn't be too hard.

[JFormDesigner]

@Jugen just noticed that you're self-assigned to this issue. Do you work on a PR?

Some weeks ago I've (partly) implemented this in Markdown Writer FX in this commit: JFormDesigner/markdown-writer-fx@4f5c45b

The MWFX implementation not complete. E.g. does not use GenericStyledArea.getTargetCaretOffset(), because it is private.

If you're not working on this, I would improve my code and submit a PR.

[Jugen]

@JFormDesigner no I'm not working on PR yet, so please go ahead ....