Error when selecting Diagram Paper Size (#470)

The error details below. I did select send report, but there was no feedback that the report had been sent so created this report.

System.NullReferenceException: Object reference not set to an instance of an object.

at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)

at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)

at SoftwareIdeasModeler.Core.CommandProcessing.ApplicationAction.Perform()

at SoftwareIdeasModeler.Core.CommandProcessing.ApplicationCommandProcessor.Execute(UnitOfWork unitOfWork, CommandDefinition commandDefinition, ActionCallback actionCallback, Object callbackTag, Boolean calledFromAnotherAction, CommandArgument[] arguments)

at SoftwareIdeasModeler.MainForm.ribbonBar_RibbonButtonClicked(Object sender, RibbonButtonEventArgs e)

at Ribbon.RibbonControl.RibbonBar.OnRibbonButtonClicked(RibbonButtonEventArgs e)

at Ribbon.RibbonControl.RibbonButton.OnClick(EventArgs e)

at Ribbon.RibbonControl.DropDownMenuPanel.ConfirmSelection()

at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)

at System.Windows.Forms.Control.WndProc(Message& m)

at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

OF=SoftwareIdeasModeler.MainForm

LastCmd=SoftwareIdeasModeler.Core.Commands.AddDiagramCommand

OF=SoftwareIdeasModeler.MainForm

NoCmds

OF=SoftwareIdeasModeler.Forms.ProjectForm

OF=SoftwareIdeasModeler.Forms.StartForm

OF=SoftwareIdeasModeler.Forms.ProjectForm

OF=SoftwareIdeasModeler.Forms.EditorForm