What is the function of this V next to the minimize button?

[Spelunky]

I click on it and nothing happens.

Version 98.0.1100.3 (Official build) dev (64-bit)

[#2 · Accepted solution]

@Spelunky That button is Tab Search Windows 10 Caption Button that appear in Google Chrome but in Microsoft Edge is not functionable .
To search tab, click on the Tab Action Menu and select Search Tab or press Ctrl+Shift+A on keyboard.

[#3]

Thanks! two things I noticed after I read your comment:
1 - on Edge, it works if you press Ctrl+Shift+A, as shown in the image. Kinda weird display in the middle there, but I think the developers are still working on the feature.
2 - I didn't know Chrome had this feature. I have it installed but I use it very little. So after I read your comment I opened Chrome to see and it actually has this command and it works as you said.