Bookmarks UI improvements

[oleg-shilo]

Thank you for helping out.

I am not sure I am sold on the new UX the PR delivers.

• It's hard to distinguish between the node coloured because it is bookmarked from the node that is selected. One needs to remember the exact selection colour. I actually think having the default selection border makes more sense.
• Selection background interferes with setting the bookmark colour. It hides it. Thus until the node gets unselected it's impossible to say if the bookmark color was successfully assigned.

Good UX and DevX:

• Though I agree that your 'sync' icon is better. I deliberately wanted it to be single-directional because clicking this button syncs only one of the involved parties in the tree. That's why I made my own icon for that. But I am afraid it becomes completely unintuitive - it's hard to say what this button means until you pop the tooltip. I will use your image then.
• Will also use your update to the converter (extra properties)

Ironically I also played with it yesterday.

This is the progress:

1. Make (remove) the border of hovered and active nodes rectangles same color as background (like in Git Changes window). It will clean up UI I decided to keep the existing UX for the reasons above.

2. Make bookmarks background under the full node, not only behind text. It will fasten visual recognition. done But I will need to update all dark theme node-icons to ensure they are not blending too much into the background as they do now.

3. Make bookmarks popup on full node right-click, not ony on text. It's disorienting now. done

   This is what I have so far (bookmarks-styling branch):

[vsopko]

Agreed with "...It's hard to distinguish between the node coloured...". I think the proper way is to remove border from nodes and define 3 colors for each state (like with flat buttons):

1. Default (or "bookmarked")
2. Mouse hovered (slightly brighter then 1)
3. Selected (more brightness then 2)

Also please look that list border was removed (available only on bottom side for expander visual splitting) and expander content slightly padded from top.

In general, it seems to me that everything is clear and the decision is at your discretion

[oleg-shilo]

Done.

I decided to keep the existing selection visual effect (with minor layout adjustments) but otherwise, all the suggestions we discussed ended up in the final solution.

Thank you for sharing ContextMenu styling. It saved me the time of repeating the IDE styling.

[oleg-shilo]

I will be closing this PR as almost all its content is now in the codebase anyway.