Combo box misuse

[fcollot]

All across MUSIC, combo boxes are used in such a way that the first item stores a text like "Select an item", and the index 0 is used as an indicator of an item not being selected. In most cases I think this is not how the combo boxes should be used. The text should be a label and the combo box should only contain valid selectable items. That way there is always a default item selected. This not only saves clicks but it also simplifies the code: currently, all toolboxes have to check if an item has been selected in order to enable buttons, execute processes etc. If you don't have a "none selected" state, you don't need all that code (which often contains bugs).
Now, if for some reason your input NEEDS an "unselected" option (ex: the toolbox selection combo), then the first item should not be "Select a toolbox", but "None" (or similar), and there should be a label "Toolbox" above or beside the combobox.