We have a discussion between UXers and developers:
UX: In a multiselect dropdown one should add/remove item to/from selection through checkbox and clicking the label. When one wants to remove all or select all use the dedicated (select/remove all) button.
Developers: In a multiselect dropdown one should add /remove item to/from selection only thought the checkbox. If one selects the label of an item; the selection should be cleared and you should only select that particular item. Additionally, hold ctrl if you want to add through label clicking, like Windows Explorer.
For instance in the below image, clicking the words "Microsoft Syncronization Services" will select only that folder, but clicking the checkbox will select it in addition to the four other selected items.
Is one of these solutions more correct or sensible?
note that its about the multiselect dropdown control. We also have checkbox groups and collection selectors