Better tooltips when hovering on tool icons and layers

[FawFuLJJ2]

Request to make this mouse hover say the layer name rather than repeating what your mouse is on:

Also, these don't have tooltips at all. Would be welcome knowing what this icon does... I must have known before but always forget and a lightning bold is not really self explanatory.

[Violet-CLM]

Instead of tooltips, JCS displays the button function in the bottom right corner. MLLE does this too, including for the lightning bolt buttons. I didn't realize the layer icons showed tooltips, that's not intentional.