Copy/paste does not work in certain situations

[Marc-Andre-Rivet]

Clicking in cell in first column with the standalone demo code (npm run build.watch + localhost:8080) does not trigger a copy. Clicking on cell in the 2nd column triggers a copy. Navigating with mouse to first column from 2nd column cell, copy can now be triggered exactly once.

There is a global onCopy handler in the controlled table. Seems like in certain situations the cell's input element may be capturing that event instead.

This may be a regression. Unsure how long this has been a problem.

[michaelbabyn]

This came up in a support ticket and I was able to reproduce in dash-table > 3.6.0. If I select a chunk of the table and then try to copy it into excel it doesn't work unless I first click on another cell in the same selection before I press ctl-c.

I tested this on ubuntu 18.04 using chrome and firefox