It’s almost impossible to use the drag handles to adjust margin and padding now. Any small adjustment of 1-15px doesn’t register as smoothly as it used to. Only when dragging the handle fast do you get a response. Try to use the padding drag handles to alt-click and drag a 15px padding. Good luck.
This new style panel should have been tested for much longer before removing the legacy style panel. I think with all these bugs we should at least have access to the legacy style panel while you work this out.
Clarification: this dragging bug is on Chrome. Safari seems to work fine, except it doesn’t hide the cursor while dragging and I can’t drag past the edge of the screen when adjusting margin-right. I would actually rather have it work like Safari now with the screen edge limitation than the erratic behaviour we currently have in Chrome.