How to make the Toolwindow setting don't export to the VSSetting file

Hi:

I have a problem with the setting of my customized toolwindow. Could somebody help me resolve this issue. 

Firstly, Let me clarify my issues:

1. I have developed a application based on the VS Shell.

2. After creating my customized project, I can launch a toolwindow to configure my project.

3. Keep the toolwindow opened, then I click the "Import/Export Setting" item to export my setting in current layout.

4.  Close my project, then click the "Import/Export Setting" to import the settings that I just exported.

5. I found my toolwindow is shown but there is no project opened.

After some investigation, I found my customized toolwindow setting had been exported to the VSSettting file. As followed:

<wm:ToolWindowView ForceCreate="DontForceCreate" IconIndex="2" IconResourceID="301" IconResourcePackage="******" Name="ST:0:0:{********}" IsSelected="True" IsVisible="True" FloatingTop="100" FloatingLeft="100" FloatingHeight="450" FloatingWidth="450"/> 

You can find the IsVisible is set to "True". So when importing this setting, the toolwindow is shown.

I just wonder, is there any attribute can set to the Toolwindow, if export the setting, the setting for this window can not be exported.

Or is there any other solution to make the toolwindow not shown after importing the VSSetting file.

Thanks

Paddy