There is no option to set a modifier such as "Hold".

For example, I'd like to unbind "Hold Sec. Mouse Button" for "Temporary zoom" and bind it instead to "Hold Mouse Btn 5" (which is a button on the side of my mouse).

I am able to remove the "Hold Sec. Mouse Button" bind, but I can only assign "Mouse Btn 5" but not "Hold Mouse Btn 5".

Several options are also missing from the preselects.