Ctrl-V in QTextEdit does not trigger the canInsertFromMimeData() function

Hi,

From the doc, when user presses `Ctrl+V` in `QTextEdit`, the `canInsertFromMimeData()` should be called and user could change the paste behavior here. From my application, `Ctrl+V` will simply directly paste the text from clipboard without calling the `canInsertFromMimeData()` function. However, if I click the `Paste` in the right context menu, the `canInsertJFromMimeData()` function will be called always. I think the behaviors of these two methods should be exactly the same.

It used to work in Qt 5.9.

Thank you!