Is there any way to anchor the Info Template to the corner of the screen/window instead of anchoring it to the corner of the feature?
Are you thinking something like this?
Here is a sample that places the info window content in a side panel. This is not exactly what you are asking for but may suffice until JS API 4.0 is officially released (it has the ability to dock the info window).
I am thinking of something like a side panel. However, I do not want it the whole length of the screen.
I think, you can try to make Infowindow as movable. Then you can drag it on any corner of map window.
I put together a sample here.
You can check this out.
InfoWindowFloatingPane - JSFiddle
See if that helps.
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