I'm going to lump this into one Feedback item, but perhaps it should be broken up.  I took some notes while attempting (and never successfully) using the manual merge dialog in VSB.  This seems really important for one main reason: many people base their themes off of your Built-In themes.  When a new release of UI for WinForms comes out, with a new control like the CollapsiblePanel, it's tricky to get that added to your existing older theme (which is the scenario I'm dealing with right now).

I've ordered these items in the order of importance (at least to me =] ).  I think the main thing is the on-screen help and terminology used to describe the items on the screen being confusing and inconsistent, but I do believe there are some bugs and/or missing features to make it functional.

- The text in the merge dialog refers to a "Destination" and a "Source" theme everywhere except on the DataGrid column which refers to "Existing" and "Loaded".  If I have a theme open (let's say MyOldTheme.tssp), and then I open another theme (TelerikMetroBlue.tssp) it triggers this dialog to open.  Which theme in that case, is the Source/Existing/Destination/Loaded?  I think this should be clarified by making it clear which is the source and destination and sticking with that terminology, or call it something like "Item Loaded" and "Item Loading".  Also, in which order should I open these two themes if my end result is to get one control or a set of repos merged into MyOldTheme.tssp from TelerikMetroBlue.tssp
- Everything is detected as a conflict.  Real conflict detection should exist where it only shows items that are conflicting (i.e. the item exists in both files but there's a change).  You can open a file, and then open that SAME exact file and every repo item is red and considered "conflicting".
- You show a comparison grid, but I can't see any way to resolve the conflicts it finds.  It doesn't let me choose which value I want, the source or destination.  
- There's a lot of text describing how to deal with the conflicts on this screen, but after reading it I was more confused than I was before.  I think this needs a lot of clarification, and should be written better.
- The "Existing" and "Loaded" columns in the grid have their names cut-off, don't support column resizing, and don't have a tool tip.  The only way I could see that they were called "Existing" and "Loaded" was by going to the column chooser, and removing the columns (since if they're added to the grid, they don't show up in the Col Chooser)
- I think the "Existing" and "Loaded" columns should be immediately next to each other for easier visual comparison of the two.  By default there seems to be a random text field thrown in between them (they can be manually re-positioned, though)
- In the column chooser there's a IsSelected column I can add - does that have something to do with the merging?  What does "IsSelected" represent? Choosing the item from the item already loaded, or the item I'm currently loading?  It doesnn't seem to do anything, but I could be wrong.