[Bug] r4031 "month wait time" not greyed out

[jamespetts]

In the schedule window, the "Month wait time" option is not disabled when the dialogue is first opened, even when the minimum load is not set. When an attempt is made to adjust this setting, it then becomes greyed out and refuses to adjust further. However, when opening the window again, it is evident that it has been altered (as 1/512 or 1/1 is displayed, depending on which arrow has been selected) and the greying out is lost again.

[Dwachs]

should work with 4036.