Change style of selected arc
Change Redo Shortcut

change the redo shortcut. Now its the same as the textEdit redo shortcut
Save/Open new improvement

When a file is saved or loaded, the directory path is maintained
for the next save/load operation
Save/Load improvement

Save and Save as method
Better dialog window
Save/Load improvement

A star '*' is added to the title of the window when the file is modified.
The name of the current modified file is shown in the title of the window.
When closing the window, a message box appears if the current file has
been modified and not changed.