Sardor Shukurov
Sardor Shukurov
Hi @govert! This issue reproduces quite reliably for us when we open a workbook in 2 windows and close the first window. This is the exception origin: 
@govert we are using Excel-DNA v1.5.1. I tried on v1.6.0-preview3 - the issue reproduces there, too.
@govert the workbook contains links to external workbooks and also uses custom functions, but no RTD functions are used as far as I understand.
@govert we cherry-picked your [commit ](https://github.com/Excel-DNA/IntelliSense/commit/9703ff6f33d36b6116338f0dc147618e9ee93041)to our fork, but the fix does not seem to be working for us.
Debug output: 
@govert it seems to work correctly when I create an add-in from scratch and reference the relevant pre-release NuGet packages directly.
@govert I just found our fork contains some additional lines of our own in ToolTipForm.cs - I commented out those and it helped! Thanks a lot for helping with this.
@govert, I know why it fixes, yes it was hard to debug and I was able to get some understanding only through studying the logs. In `FormulaEditWatcher` when `Unfocus` triggers:...
https://github.com/Excel-DNA/IntelliSense/pull/125
@govert one of my colleages informed me today that the arguments tooltip gets hidden even with my proposed fix with a slight change to the above steps: 1. Follow the...