If you slingle click on the value and drag the mask feather, or any other value in the time line, will increase while moving to the right and decrease while moving to the left. There is no slider but you should see a hand with a double ended arrow when you hover.
If you double click the value you have to type it in.
I know but i've got another mask feathering, I HAVE to right click on mask feathering and then click Edit value before I can feather the mask.
The picture you showed, did I have when I installed then I clicked something strange and now I HAVE to right click on mask feathering and then click Edit value and that's annoying. So I want the mask feathering back you showed me on the picture.
What happens when you select your layer and press the M key twice? Or M then F? Or Option/Alt-Shift-F (for feather)?
You must be pressing Command-Shift-F, which brings up the Mask Feather dialog box (which cannot be scrubbed).
Right-click the timline column headers and bring back the "Switches" and "A/V Features" column...
Thank you so much!!