First of all, what is the intent of highlighting, boxing and favorites? Is it to remind oneself which folders one keeps interesting files in? Or which folders one should remember to check regularly? Or which folders have work to be done? I keep a very tidy hierarchical structure of my file system. Even though I can't necessarily remember which particular file or folder I've encrypted (i.e. attributes), I do know where I keep which kind of files, which folders I download items to and where I've stored my work (i.e. the function of a folder). I don't need visual indicators to keep track of that. But some might, I guess, if they're less focused on structuring their file system. It would thus be interesting to see a screenshot or two showing how these coloring features are applied in practice for those who use them.
I similarly wonder at the conceptual difference between highlighting, boxing and favorites. Why not simply let the user create his own labels (e.g. "music") and choose an appropriate text style (e.g. bold) and/or color instead of predefining a certain set of labels (i.e. "favorites")? This would be more complex, of course, but also more flexible, if I correctly understand the function of these visual indicators.
Generally, I understand the line of thought that the tree view and the file list view serve different purposes (i.e. where versus what). The problem is that both views show the same items (in the case of folders). For all items that appear in both views (i.e. folders) I strongly believe that these should have the same visual appearance. Otherwise one view seems to indicate one thing (e.g these folders are encrypted) while the other indicates another (these folders are not encrypted). The same reasoning applies to all visual indicators, except those that are a natural function of the view (e.g. only the tree view can have "+" buttons to indicate hierarchy and boxing colors). To me, at least, this inconsistency between views (which I still believe it is
It might be useful to explain how I use the views. Basically, I navigate at the tree view (to get the overall perspective), and move to the file list view only when I've entered the intended folder. At this point, the tree view shows which folder I'm in, while the file list view shows the contents of that folder. Selecting a folder in the file list view should not select the same folder in the tree view, both because that would invalidate the purpose of the tree view (showing which folder I'm inside) and because it splits the active focus between the two views (while I'm only working in one). As such, I see the tree view as a navigator on the folder level, and the file list view as a navigator on the file level. Thus it wouldn't make sense to add files to the tree view. But it would, however, make sense to add visual indicators to the tree view, since this view is supposed to aid navigation on the folder level. Without knowing which folder contains the desired attributes, I have to resort to the file list view to find the correct folder, only to switch back to the tree view again to navigate the hierachy deeper. Shortly put, I have to jump back and forth between the views until I reach my target. Compare this to simply navigating the tree view until I find the correct folder and then only switch to the file list view once I'm actually going to manipulate files. That's the way I prefer to work.
On to the implementation: Because the difference in thought lies in how the views are regarded, rather than which particular color feature should apply to which view, I'm thinking that perhaps the best solution is simply to have a checkbox for whether you want the color filters to also apply to the tree view. This won't allow fine-grained control, but on the other hand it will be simpler to understand and utilize. And I can't really imagine why someone would want one attribute to appear visually in the tree but not another. That will only lead to chaos. Which eventually leads to the dark side and killer bunnies and all that. And we don't really want that, do we?
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