In Function Editor you cant move the timing of a key while holding ALT - if you have enabled “straight” spline from the Bezier Editor.
Which by the way should be fusioned into one functioning united and better graph editor.
Try look at Autodesk Maya.
They have the best out there. Please get inspired and make this work at least.
Why cant you change the keyframes settings in Function Editor, while you can in Bezier Editor. Im talking about the tab with “Corner”, “Straight”, “Smooth”
Best regards Troels