Begins to validate the input data for editing the selected node to see if it has changed.
Completely validates any changes to the selected node and determines if the data is "new". If so, the apply button is enabled. Also makes an aesthetic change to selecting nodes. Selecting no longer makes the node appear to move right.
Merge pull request #33 from Mctalian/patch_8

Resolves Issue #8: Apply button is no longer clickable unless new data is present in the selected node edit box.