Microsoft is now testing another new Windows 10 Mobile cumulative update, after releasing build 10586.164 officially for older Windows Phone handsets handsets. This new cumulative update is currently being tested internally, and much like previous cumulative updates, brings a more bug fixes and performance enhancements.
WinBeta can confirm that the new cumulative update finally fixes a bug that involved closing an app that was launched from the Apps List. Currently, closing an app launched from the Apps List would cause the background to essentially un-dim itself, making it hard to read text when using a light background. This issue is fixed in the latest Redstone builds, and is now fixed in the upcoming patch for current branch users.