Unchanged text is usually not that interesting during an edit conflict, but people should still be able to view and edit that if they want. This ticket is about the ability to expand and collapse these text blocks as needed.
 By default, all unchanged text blocks are collapsed
 If you click on the arrow, the corresponding text block expands
 If you click on the arrow of an expanded text block, it collapses
 If you are in editing mode, you cannot collapse the text block.
 If you click the checkmark after editing, the text box stays expanded
 The text that is shown in the collapsed view, should be the same as in the current edit conflict ("start text .. middle .... end text")