Regarding [685ac30727] - I installed TkTable and ran demos/basic.tcl.  I
was not able to make any overflowing text appear in any other cells.

I am not sure I was doing the right thing in that demo, but I think it
still works as expected with the change to XCopyArea i the pixmap-to-pixmap
case.

I was not able to move the cursor in a cell with the arrow keys, as they
move the focus to a different cell.  But I am assuming that is the
expected behavior.