Hello,
The whole problem is that playing with the "Visible" property of any control while inside UpdatePanel does have its side effects. Setting visible to false for any control completely removes it from the control tree and it is not rendered at all on any page, so complex controls like WebDiaogWindow for example amy incur side-effects because of that.
I started from your code and instead of using the Visible property, I used the WindowState property of the control and got much better results. Just make sure you remove the Visible = False hardcoded property in your ASPX declaration first, and then show/hide the dialog window with:
protected void Page_Load(object sender, EventArgs e)
{
WebDialogWindow1.WindowState = DialogWindowState.Hidden;
}
protected void Button1_Click(object sender, EventArgs e)
{
WebDialogWindow1.WindowState = DialogWindowState.Normal;
}
protected void Button2_Click(object sender, EventArgs e)
{
WebDialogWindow1.WindowState = DialogWindowState.Hidden;
}
In any case, you can also submit your scenario as a bug through our official Bug Report system located here:
http://devcenter.infragistics.com/Protected/SubmitSupportIssue.aspx
Hope this helps.