Debugger beta testers need to visit the debug beta page for a new upgrade installer

Documentation for  version is currently incomplete. Some of the following features apply to the debugging version only
1) The serial window did not automatically switch when switching between debugger Local and Remote speeds. Therefore the debug session would appear to be failing.
Manually changing the speed in the serial window would cause debug to start working but if the Arduino was waiting for "F5 Continue" then things still appeared to be failing. using the Serial Tool to send a 'c' character would solve the problem.
2) Fix: Unable to click the debugger "Expression Watch" window. Doh!
3) Build Folder - Quick Access Hyperlink.  "Tools>Options>Compiler>Show Build Folder=True" provides  hyperlink to the build folder in the output window (see below).
CTRL+CLICK the link to open a file manager for the build folder inside Visual Studio. With this option set to True, the "build folder" link will be displayed after each compilation.
The image below shows the build folder after CTRL+clicking link in the compilation output window (Micro Build).
Tools Options Build Folder
4) Better/clearer compiler error message handling from library sources.  Normally there will be two lines of output text per error. Double click the 2nd (last) line of an error to GoTo source
5) Support for boards.txt that use shared cores.
6) Boards with dashes in name failed to show a menu item and where not available as Visual Studio User Interface Short Cuts and Macros.
7) Optional support for WinAVR.
set "Tools>Options>Visual Micro>Locations>WinAVR" to the [winAVR]\Bin folder
Tools Options WinAVR Location
8) Fix: After re-starting Visual Studio, single project solutions did not always remember which board and port was selected.
9) Fix: Debugger breakpoint Hit Count Frequency Type
The frequency of hit counters was set to millis() and could not be changed. You are now able to switch between a simple count (default) and a millis(0 timespan. Use the project property "Hit Counters" to set this property. The project setting is applied to all breakpoints that have a hit count.
Example:
Breakpoint with "Hit Count = Multiple of 100"
When the setting is "Count", the breakpoint will be actioned every 100 hits.
When the setting is "Milliseconds", the breakpoint will be actioned every 100 millis()
10) Fixed: Flashing IDE frame and sluggishness during debug compilation
11) Fixed: Long Pause after Memory and Dis-assembly Report. Thanks to CapnBry
12) Fixed: Breakpoints without watch expressions raised compile error
13) Writing back to mcu variables from the debug expressions window. Thanks Heinz Kessler :D initial documentation here
14) Default breakpoint throttle increased to 80ms from 50ms. This setting can be disabled but allows you to place as many breakpoints together and/or in the "16mhz" loop() without worrying about overloading the serial buffer or causing the PC display to fall behind "real-time". The setting is really for new users or simple non-time critical debugging.
15) The tool tip that is displayed when hovering over a breakpoint in the debugger watch expressions window clearly shows the line number of the breakpoint in the source code snippet. The snippet has been altered to show 8 lines prior to the breakpoint, the breakpoint code and 8 subsequent source lines
16) New "Tools>Arduino>Other Serial>Monitor COM..." menu allows serial monitors to be opened without affecting the current projects upload port. read more
17) Teensy and other platform:core