Get Coders dialogs right

The Coders dialogs are not working properly in these situations:

1. There are coders defined in the configuration file; In the “Coders” dialog, the button “New” is pressed; in the “Edit coder information” dialog, either button “Cancel” or button “Ok” is pressed, without filling the fields; in the “Coders” dialog no coder is selected and either button “Cancel” or button “Ok” is pressed. Then, the file selection dialog appears, like there was a coder selected. The problem persists and, when the user required saving the project again, the file selection dialog appears immediately, without proposing to select a coder.
2. There is no coder defined in the configuration file; the user requires the saving of a project. It is impossible to quit the “Edit coder information” with the button “Cancel”.