BUGFIX: Stop click event propagation on selected element in select box header

[grebaldi]

fixes: #3057

The Problem

Hard to pin down, but I'll try: The issue described in #3057 relates to the AssetEditor which uses the <SelectBox/> component for input. The <SelectBox/> component uses the <DropDown/> component for rendering. The <DropDown/> component understands a click on its header as a request to toggle its expanded state. When expanded === true, the <SelectBox/> changes its header into a search input, so the user can search through the available select options.

Now, the AssetEditor kind of misuses the <SelectBox/> for its purpose. It narrows the available select options to the currently selected asset, so the <SelectBox/> displays the latter properly. This however means that the behavior described above leads to a search input, but only one available select option: the currently selected one. (Side note: On input, the search is still being performed, the <SelectBox/> simply does not show the resulting options)

The Solution

I've tried to correct the behavior of the AssetEditor, so that it shows the search results, but with no luck.

So, I ended up implementing the suggestion from #3057. Through stopPropagation, a click on the currently selected option won't toggle the underlying <DropDown/> component any longer.

[Sebobo]

Great, thx!