This is true in both 2.4.3 and 2.5.beta when using IE7 (other browsers not tested). When FCK_TOOLBARITEM_ONLYTEXT is used for anything derived from FCKToolbarSpecialCombo; the state of the control will not be shown in the grayed out disabled state when in Source View mode. (Can be duplicated in 6th example for plugins) I think this is really a flaw in whatever skin is being used. If you find the line (412 if default skin) in the 'fck_editor.css' file of the skin that looks like:
.SC_FieldDisabled .SC_FieldButton, .SC_FieldDisabled .SC_FieldCaption
and change it to:
.SC_FieldDisabled .SC_FieldButton, .SC_FieldDisabled .SC_FieldCaption, .SC_FieldDisabled
That fixes it for me.