shortcut for colourbar limit buttons

Something I often do is scroll up/down the layers/slices looking at a variable (e.g. K) by using the keyboard arrow keys. I would like to have a keyboard short cut to change the colour scale (i.e. not have to click "scene limit" then re-click on the layer name to re-enable keyboard scrolling).

Other keyboard shortcuts would also be useful, such as switching from select mode to line mode etc.