Sure, that layout makes a lot of sense.

Regarding the default tool, it is there mainly as a way to escape/cancel the current tool.

The default when opening that page should be the drawing or painting tool.
The new shape of the mouse pointer feels strange to me. It is not clear when it is turned on and when it is turned off.
The erase tool sets the label value to 0, but when I go back to an effect I have to reselect the label I was working with.

Please use the eye instead of a check box to show if advanced is visible or not

Actually I think a collabsable group box is more appropriate than the eye icon for the Advanced tab (it has the triangle that rotates to show the status).

agreed. That is what Isaiah did for TractographyDisplay , 0001296 and what Julien suggested:"In order to be consistent with other modules, I would advice against the eye or the checkbox, but to use a ctkCollapsibleGroupBox (or ctkCollapsibleButton). "

Addressed in revision 17970.

Fixed the erase - it now works as in slicer3 where it toggles the paint color without exiting the current effect.

Was not able to make paint tool active when starting - we may add this later, but I don't think it is too critical.