Error on close with page number selected

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Open a file
2. Scroll to top down
3. Erase text from "tsPageNum"
4. Close App.

What is the expected output? 
Aplication close.

What do you see instead?
Exception: "System.InvalidCastException: Conversion from string "" to type 
'Integer' is not valid. ---> System.FormatException: Input string was not in a 
correct format.
   at Microsoft.VisualBasic.CompilerServices.Conversions.ParseDouble(String Value, NumberFormatInfo NumberFormat)
   at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(String Value)
   --- End of inner exception stack trace ---
   at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(String Value)
   at PDFView.PDFViewer.tsPageNum_Leave(Object sender, EventArgs e)
   at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
   at System.Windows.Forms.ToolStripControlHost.OnLeave(EventArgs e)
   at System.Windows.Forms.ToolStripControlHost.HandleLeave(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnLeave(EventArgs e)
   at System.Windows.Forms.Control.NotifyLeave()
   at System.Windows.Forms.ContainerControl.UpdateFocusedControl()"

What version of the product are you using? 
The lastest from the repository.

On what operating system?
Windows 7 profesional 32 bits.

Please provide any additional information below.

Original issue reported on code.google.com by ignacio....@gmail.com on 12 Mar 2014 at 7:40

[GoogleCodeExporter]

The steps are:

1. Open a file
2. Erase text from "tsPageNum"
3. Scroll to top down
4. Close App.

Sorry!

Original comment by ignacio....@gmail.com on 12 Mar 2014 at 7:50