Keys option: Add Hue increase/decrease.

58261a34dd73d0a623c210b3cbb30f2d0d7980b9 added the necessary code except for the UI part.
Keys page: Modifying the mouse button wasn't marking the page as modified.

Fixes #3848.
Cosmetic: Disable the text consistently in the Sync Render Settings page.

Fixes #3851.
Fix: Editable list views were scrolled left each time a cell was edited.

The bug was hidden before 4efc99381f0d68fbb66e00f0a40a69948785e18e.