Thanks for the info.

Visual Micro does not have any involvement in the code editor. It simply gives Visual Studio folders and defines for its standard C++ intellisense. It would be too complicated to interfere with UI side of the the Microsoft C++ intellisense in the code editor and be too difficult to debug issues.

So looking at your issue I have a few initial comments/pointers...

1)
It would be useful to try the same syntax in a new lean project. If the same problem exists then pls zip and email the project to info[at]visualmicro.com along with a link to this project and list of libs to install to text 

2)

If the same problem does not exist in 1) then email your entire project if possible.

3)

Microsoft is responsible for the intellisense system unless you have installed another extension that is doing what I have said Visual Micro avoids. Please use help>about to confirm what you have installed.

4)

Please use help>about o confirm your VS version.

Summary

Note that it is possible that you have an intellisense error that builds okay. The VS intellisense is not 100% perfect but in most cases we can add a workaround to visual micro to avoid the red squiggles etc.  However, we would not expect a line with red squiggles to crash when viewed therefore we have two different and supposedly unrelated discussions.

Hi,

Please ignore the intellisense error for a moment and don't hover the red squiggles.

Ensure the tool bar is set to Release and not Debug and then click Build.

We need to see if the build is working. It should be the same as the arduino ide.

The intellisense is a different discussion so this will give us a base line.

Building also provides more accurate intellisense although I don't expect it to resolve the intellisense error you are seeing.


Info

You are not missing anything, the issue is that the visual studio intellisense doesn't understand some syntax such as PROGMEM, hence the red squiggles. 

The lock up could be that visual studio is searching your installed tool chains and trying to build the intellisense indexes but a virus checker is causing it to grind to a halt. Did you check task manager processes during lock up to see what is consuming cpu?

After you confirm the build same as arduino we can look at the intellisense some more. thanks

I tried uploading it to the Arduino, and the added fonts also still work correctly. So I can continue working on my software, as long as I don't accidentally drag my mouse across those false errors.

It locks up for me to in vs2017 15.8 preview 3 so we will see if same exists in the new preview 4

Building removed all squiggles from the definition and PROGMEM was fine. However the squiggles and hang happened for the  myGLCD.setFont(SevenSegment96x144Num) call. 

I suspect this is because your font defs are over 8000 chars per line or some other memory issue when visual studio attempts to show a intellisense hint for the definition of some so wide.

It's possible that a simpler non-arduino windows c++ example without PROGMEM would also give the same result in a  visual studio c++ project (not using visual micro). If this is the case it will be easy to report to microsoft.