This changeset modifies the layout editor such that it writes attributes in a certain order: * id * style * layout_width * layout_height * other layout_ attributes, sorted alphabetically * other attributes, sorted alphabetically The layout editor will produce attributes in this order when - New widgets are dragged into the layout - Widgets are moved in the layout - It will also insert attributes in the right place when they are set as the result of (for example) using the context menu actions. Note that this ordering is applied unconditionally - there is no user setting to turn it off. However, note that the current behavior is random - moving a view for example will scramble the attributes (in an order which is related to hashkeys in a map), so the option would be "sort attributes logically" versus "sort attributes randomly"; if we want an option to "leave attribute order alone" that will need to be implemented. Limitations: - This does not yet modify the formatter to reorganize attributes. Thus, Ctrl-Shift-F to reformat the XML will not change attribute order. - It does not fix the problem that the XML model updater does not respect the formatting settings (such as one newline per attribute) when manipulating attributes. This will be addressed/worked around in subsequent CLs. Implementation Note: The Eclipse XML model updater will unconditionally *append* any new attributes. We take advantage of this to perform attribute sorting by ensuring that we always insert new attributes in the right order. We also check for existing attributes and any which fall lexicographically later than the new attributes are removed and reinserted in the right sequence. In order to avoid performing these removals and additions repeatedly on a node when we set multiple attributes, and to avoid flushing attribute changes *immediately* (which was the case until this), we now queue up all pending attribute values in the nodes and apply them at the end when all attribute changes for a given node are known. Change-Id: If39f8c29f26e281f7c6622a31e11ba49724d274a