Make sure that the state is consistent after an undo operation
Make sure that the state is consistent after an undo operation

When performing an undo operation, further changes should not be
accounted to the then active action. Therefore take a snapshot
which resets txt->current_action to NULL.

twinshadow/vis,twinshadow/vis,clehner/vis,rychipman/vis,trengrj/vis,8l/vis,aoloe/vis,cpehle/vis,rychipman/vis,aoloe/vis,trengrj/vis,8l/vis,clehner/vis,cpehle/vis