Fix some toc ui glitches:

Fix some toc ui glitches:

- revert r26360, because this causes irritating flickering, and reset the slider in updateView instead,

- disable also the sort checkbox and the slider when the list and combobox are disabled,

- disable the keep checkbox when the type is not navigatable, as it doesn't make sense to keep something that won't change.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@29477 a592a061-630c-0410-9148-cb99ea01b6c8