Using Qt 4.8.3 (and whatever Webkit sits behind that). Issue happens on Windows and Linux at least. Set isContentEditable(True) on a QWebView/Page. Create a paragraph with some text in it. Copy some text, pick a point within the paragraph block (not at the end) and choose paste. Then without clicking mouse, hit a key. Webkit will now draw a phantom "selection" from the point after where the space was inserted until the end of the block. It isn't a "real" selection in that choosing to copy etc will not give you that text, it is just an annyoance. The user can make a "real" selection elsewhere in the document, scrolling the page offscreen etc will not clear that painted selection. The ony thing that can be done is to create a selection with the cursor that overlaps the entire phantom selection, and then undo it.
The Qt port has been removed from WebKit, resolving this bug.