* How to bind key to specific brush preset?

* How to bind key to specific to specific opacity (I need 20%, 50%, 100%, the problem with 'I' and 'O' is that they are relative, not absolute)? It can be solved with custom brushes, but see the last note about customizing, and also it requires to create multiple versions of each used brush.

* How to delete the layer with hotkey (not so often used, but it's not extremely rare)?

Which hotkey chain prefix can be safely used by user, to avoid conflicts with existing and future default hotkeys (like ',' in vim)?

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One more problem with non-default hotkeys (and brush presets too) is management on different devices, which is not a problem If I use 2-3 custom hotkeys, but creates problems when more than 10 custom settings are used. And it requires personal control version (git/mercurial/svn), not very common tool for artists. So I think it's not very wise to force each user to create custom blur tool, and custom shortcut for lasso, and so on. There are other problems with frequently used, but non-standard hotkeys. Better to have standard long chords Ctrl+Shift+Alt+A+B+C, with user custom for most frequently used, than no shortcuts for most tools at all.

Also hotkey for layer visibility is really needed (current layer or specially binded to specific layer during work on pciture). Switching layer visibiliy - very often used operation, and layer buttons are small and hard to click with stylus

Layer delete and layer visibility are in 3.0, the rest isn't implemented yet because we haven't figured out the best way to do this.