http://bugzilla.lyx.org/show_bug.cgi?id=3346
The fix is simply to clear the dirty flag of the tabular clipboard on normal text copy. Seeking 2 OKs. A/
Index: CutAndPaste.cpp =================================================================== --- CutAndPaste.cpp (revision 18850) +++ CutAndPaste.cpp (working copy) @@ -628,6 +628,7 @@ copySelectionHelper(cur.buffer(), pars, par, cur.selEnd().pit(), pos, cur.selEnd().pos(), cur.buffer().params().textclass, cutstack); + dirtyTabularStack(false); } if (cur.inMathed()) {