feat: expand brush style menu, fix inconsistencies

[Kneemund]

• Should be merged alongside feat: multiplicative marker blending #1730.
• Alternative to Feature: Highlighter that works on PDFs #1602.
• Fixes some inconsistent margins and separators.

There has been some discussion in #1602 on if the highlighter/marker brush style should be split off into a separate pen in the bottom sidebar. As I've explained there, I think that this is a compromise that makes the highlighter easily accessible while not duplicating parts of the UI and engine.

[JemmeCh]

Hello! I just started to use RNote and I was bumped out that there's no highligther tool. I spent the past 30mins reading about all the issues/merge requests you made and I think you found a good solution, especially this new UI design. It makes it easier to switch tools and removes convoluted submenues.

You mention in #1602 that your highlighter proposition adds an alpha value to the marker. In the spirit of this UI redesign, I think the seperation of the marker and the highlighter could be better since switching between highlighter mode and marker mode would be easier.

Maybe I'm missing how the actual switch would occur in practice... Would you be so kind to show us how it would work?

[Kneemund]

You mention in #1602 that your highlighter proposition adds an alpha value to the marker.

Hi, my set of PRs do not involve any alpha value modifications, the highlighter can use colors of any opacity. It uses multiplicative blending and also works with fully opaque colors.

Maybe I'm missing how the actual switch would occur in practice... Would you be so kind to show us how it would work?

Here is the demo of the workflow I propose.

• I'm switching from the regular brush to the highlighter brush in the left sidebar, which also changes the stroke width (it is saved for every brush individually).
• I'm using the default, fully opaque colors which I would also use with the regular brush.

highlighter-full.mp4

[JemmeCh]

You mention in #1602 that your highlighter proposition adds an alpha value to the marker.

Hi, my set of PRs do not involve any alpha value modifications, the highlighter can use colors of any opacity. It uses multiplicative blending and also works with fully opaque colors.

Maybe I'm missing how the actual switch would occur in practice... Would you be so kind to show us how it would work?

Here is the demo of the workflow I propose.

* I'm switching from the regular brush to the highlighter brush in the left sidebar, which also changes the stroke width (it is saved for every brush individually).

* I'm using the default, fully opaque colors which I would also use with the regular brush.

highlighter-full.mp4

Ahhhhhh ok I see! So the current Marker brush with description "Mark underneath other strokes" would be replaced by your implementation. Thank you for the clarification, I really appreciate it!