I want to make split width 1px, just solid black line, and in this case, hitting into a zone of 1px width will be very difficult. It was great to be able to adjust the width of the hit area larger than the handle content size, but now it is not possible to do.

This behaviour is inherent in many editors, like VSCode and other, where the split is made by one vertical line.

My suggestion, add a new property, for example handleOversize which will add extra space for hover and press events to handle.

I am currently preparing a patch for this. Works great for me, but I'm still testing it.