Undo and Redo not working properly #56
Description
Undo key function (CTRL + Z ) does not work when there are only two blocks in the workspace.
Also Undo removes more than two blocks from the workspace, and Redo only brings back one of the blocks. For example, if the last two blocks brought to the workspace are the Print block and the Text block in that order, Undo will remove both blocks at the same time and Redo will only bring back the Print block.