Improve double spin box editing behavior

[SamVanheer]

one little quirk though if you could fix it in the next update
when you backspace a number in the bones field X Y Z, you can't add a number because it gets replaced by a 0, and being the text space limited to that amount of numbers (7 numbers + the comma) you're basically forced to highlight the number you want to change because it doesn't let you add one
if you could either leave the space blank when you backspace on a number or either get the next number be replaced by the one you want when you type it would solve the issue easily 👍 
this only because backspacing and adding a number is much faster than highlighting them with the mouse or shift+arrows
it helps on fast edits

See https://discord.com/channels/291678871856742400/484363370640703509/894626223303577670