Add dispatcher timer to avoid running expression too frequently
Code clean up based on code review
Remove a logging message
Merge remote-tracking branch 'upstream/ChocoButter' into ChocoButter
Merge remote-tracking branch 'upstream/ChocoButter' into ChocoButter
Add comment for the use of DispatcherTimer in HomeWorkspaceModel.Modified()
Merge pull request #827 from ke-yu/ChocoButter

Use DispatchTimer in Modified() to avoid the flood of graph updating