Key Editor - Edit Active Part Only

In Key Editor we have button Edit Active Part Only. What it means? It means that you can select events of only active part if button is pressed or select events of all parts if button is not active. The same is written in manual.

I think there is a little misunderstanding. Button is named Edit Active Part Only, but it affects only Select function, not any kind of editing. So the button should be named Select Active Part Only, because the only thing I can do on parts, is selecting events of all parts and change their position, length and velocity (drag leftmouse while holding Ctrl+Shift), not the velocity and other controllers in controller lane.

If it’s not an issue, then it could be a feature request and I hope I won’t be alone on this need.

But it looks like an issue anyway. For example, if button isn’t active, you select all events of both parts and do Tilt Left in controllers lane on Velocity controller. What you expect if button Edit Active Part only is inactive? Right - you expect that tilt would affect both parts, but it doesn’t. It works on active part only even button isn’t active and you have selected events of both parts. Strange, stupid, bad and wrong.

So if I have selected some 5 parts and need a little crescendo on all parts, even I have them selected, I must tilt the velocity of them all separately one by one.

And now the real issue!

While this button affects only Select function, if you select all events of all parts and then make this button active, you still have all events selected and can change position, length and velocity (drag leftmouse on events while holding Ctrl+Shift). Yes, you can change everything on selected events even button isn’t active, but you cannot edit controller events of the same controller on all selected parts.

Logically would be if while button isn’t active and I have opened two or more parts in Key Editor and I draw line, for example, in CC1 (Modulation) controller lane, it should affect all selected parts - the same controller should be drawn in all parts, but if button is pressed (active), the drawing should affect selected part only - as it is mentioned in its name Edit Active Part Only.

Very inconsistent behaviour I agree. I have just adapted my workflow to these strange inconsistencies.
Well done for explaining this in such detail.
If Edit Active Part Only is not activated, editing controller lanes should edit all selected parts.
This should be the case with Note Expression also.

As it is, if Edit Active Part Only is not activated, changing the velocity in the controller lane only edits the part indicated in the Toolbar. However, with the Edit Active Part Only in the same state, editing the velocity in the Info Line, edits all parts.

The OP is right in regards to the button being more about selecting not editing. If it was the latter, I could for e.g. select 5 parts, open the Key editor, select all notes, activate the Edit Active Part Only and by changing a parameter and edit the Active Part Only. But this does not work. I must activate the Edit Active Part Only and then select the notes to be edited.

This behaviour is not intuitive.