Feature: half page scrolling

[ViridiFox]

Description

adds Ctrl-u/Ctrl-d for scrolling half a page

Issue

Closes: #765

Testing

If relevant, please state how this was tested. All changes must be tested to work:

Please also indicate which platforms were tested. All platforms directly affected by the change must be tested:

• Windows
• macOS
• Linux

Checklist

If relevant, ensure the following have been met:

• Areas your change affects have been linted using rustfmt (cargo fmt)
• The change has been tested and doesn't appear to cause any unintended breakage
• Documentation has been added/updated if needed (README.md, help menu, etc.)
• The pull request passes the provided CI pipeline
• There are no merge conflicts

[ViridiFox]

Is there a way to get the height of the dialog, to be able to calculate half a page?

[ClementTsang]

Is there a way to get the height of the dialog, to be able to calculate half a page?

Not yet off the top of my head, would have to store that somewhere when drawn, which is something I wanted to do in the future for stuff outside of just widgets.

[ClementTsang]

Sorry for the delay btw, I'll try to review once I get internet up where I am.

[codecov-commenter]

Codecov Report

Merging #774 (4a726ce) into master (2e0771d) will decrease coverage by 0.08%.
The diff coverage is 1.81%.

@@            Coverage Diff             @@
##           master     #774      +/-   ##
==========================================
- Coverage   24.12%   24.04%   -0.09%     
==========================================
  Files          60       60              
  Lines       12982    13030      +48     
==========================================
+ Hits         3132     3133       +1     
- Misses       9850     9897      +47     

Impacted Files	Coverage Δ
src/app.rs	0.04% <0.00%> (-0.01%)	⬇️
src/canvas/dialogs/help_dialog.rs	0.00% <0.00%> (ø)
src/constants.rs	0.00% <ø> (ø)
src/lib.rs	6.94% <0.00%> (-0.03%)	⬇️
src/app/states.rs	61.43% <100.00%> (+0.25%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[ClementTsang]

LGTM for the most part. I added an extra field to track the height and fixed a tiny bug with menu scrolling sometimes overshooting (the name max_scroll_index is a bit misleading, I'll fix that in a future commit).

@all-contributors please add @ViridiCanis for code

[allcontributors]

@ClementTsang

I've put up a pull request to add @ViridiCanis! 🎉