Arguments tooltip is lost when certain topmost window steals focus

[sshukurov]

Hi @govert,

Our team has been struggling with an unpleasant issue when at times the arguments tooltip doesn't pop up when needed. We tracked it down and created a minimal repro:

Steps to reproduce:

1. Follow the "Getting started" guide in https://excel-dna.net/
2. Add an ExcelArgument attribute to name parameter of SayHello method, e.g.: [ExcelArgument(Name = "Name", Description = "Enter your name")]
3. Build and run the addin
4. Load ExcelDna.IntelliSense[64].xll
5. Focus on a cell and press Windows key and plus sign - Magnifier appears
6. Close Magnifier (optional)
7. Type =SayHello(

Expected: Arguments tooltip must show up.
Actual: It does not show up, closing the Magnifier doesn't help.

More investigation by our team:
We turned on diagnostic logging and saw that the problem roots in FormulaEditWatcher.cs. It appears that it normally expects events in the following order: Focus > Show > Unfocus > Hide. In our case however, we saw events in the produced log in Focus > Unfocus > Hide order.

We attempted to add some compensating code to IntelliSense and it helped:

If that works, I could submit a pull request. Otherwise, we would love to hear your advice on this matter.

[wh1t3cAt1k]

The sporadic missing tooltip window issue reproes quite stably for several members of our company (all with multi-screen setups), albeit not using the screen magnifier, but in their logs, the sequence of events is the same.

It's been occurring more frequently recently than before, which might be related to a recent Excel update.

[gmichaud]

On my side, the issue is especially obvious when doing a demo of our product on a Zoom/Teams call. Both products have some sort of top-most window/UI that may be interferring with focus the same way @sshukurov is able to with the Magnifier.

[govert]

Hi @sshukurov - Yes, I can reproduce this too.

All of the state tracking for the windows is just derived from what I could see happening, so I'm not surprised there are scenarios where it goes wrong.

A pull request would be very welcome. Do you understand why your suggested change would fix the event scenario Focus -> Unfocus -> Hide, since we don't do currently do anything in Show or Hide anyway?
I can try to track it down with a bit more logging, but I'm sure you've noticed how tedious it is tracking and debugging this kind of UI interaction.

[sshukurov]

@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:

• _formulaEditFocus becomes None
• FormulaEditWindow would return IntPtr.Zero
• CurrentPrefix is set to null

Consequently in IntelliSenseDisplay:

• _argumentsToolTip doesn't get initialized
• FormulaEditTextChange events are not processed

So in Show I'm simply instructing we regained focus if we thought it was lost, and vice versa in Hide. I might be wrong but feels like window focus and input focus might mean different things 🤔?

What I don't actually understand is why the need for Show and Hide handlers if they are currently effectively a noop? Was that intentional or were they added with a look to the future?

[sshukurov]

#125

[sshukurov]

@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 "Getting started" guide in https://excel-dna.net/
2. Add an ExcelArgument attribute to name parameter of SayHello method, e.g.: [ExcelArgument(Name = "Name", Description = "Enter your name")]
3. Build and run the addin
4. Load ExcelDna.IntelliSense[64].xll
5. Focus on a cell and press Windows key and plus sign - Magnifier appears
6. Type =SayHello(
7. Press ALT + TAB to switch to another program
8. Press ALT + TAB again to switch back to Excel

Magnifier must be kept open to be able to reproduce this one.

Surface investigation revealed that the tooltip gets hidden here because of Unfocus event, and strangely neither Focus nor Show does not fire upon ALT + TAB to switch back to Excel.

My first thought as a potential remedy was to change Unfocus handler to noop:

I'm slightly afraid, however, that this change might break existing functionality. I'm completely unaware for example, whether those events trigger in the same manner in different versions of OS and/or Excel 🤔

[wh1t3cAt1k]

@govert we're merging @sshukurov 's changeset into our fork of IntelliSense, including his last screenshot... Please let us know if you have any reservations or concerns about it

[govert]

@wh1t3cAt1k No, I have no particular concerns with using only Focus and Hide as the event pair.
If you update the PR here I'm happy to merge in for the next version.

@sshukurov You said:

What I don't actually understand is why the need for Show and Hide handlers if they are currently effectively a noop? Was that intentional or were they added with a look to the future?

I don't recall the details, but I presume I added cases to allow logging of any event that might be useful, then tried to use the logging to figure out a good pair to do the tracking.

I have no insight about other Windows or Excel versions.

[sshukurov]

@govert this issue had been fixed for us for a while, before it re-surfaced recently with exactly the same symptoms. Closer investigation revealed that the regression happened after the changes made per #123.

Our team troubleshooted this and we came to understanding that EVENT_OBJECT_LOCATIONCHANGE was necessary for the arguments tooltip to work properly but the event was replaced in the issue mentioned above.

We referred to the official docs for the event, where it is said to be triggered for caret and window objects:

That knowledge allowed us to assume we could re-enable the handling of it, only in the context of "caret" objects - to restore the proper behavior of the arguments tooltip, at the same time keeping the fix for #123.

We already made the relevant changes in our fork and got approval from our QA team. I'm going to proceed with a pull request to this repo and shall wait for you further feedback.

cc @sbolofsson

[sshukurov]

#130