Thanks. All these scripts are already tried since this is usual method of closing window. But adding button and opening window is controlled by code provided by Laserfiche. So we can not change that. We can only modify custonactions.xml. That's why checking if there is any code to close window also.

Oh, I missed that this isn't really a new window but just a Web Access dialog.  Since those dialogs are loaded into an iframe, window.close() isn't going to work.  What you need to do is to call .Close() on the dialog object.  The name of the dialog object should be passed to your aspx page in the "dialog" query string parameter, and this will represent a Javascript object that lives in Web Access.

So, you would run something like:

window.parent.waWindow.<%= Request.QueryString["dialog"] %>.Close();

I had a feeling that I'll need to use the same object. I had tried following code. Let me look into implementing your solution.

 DialogPage dp = new DialogPage();

            dp.ValueToSet = "";

            dp.Closed = true;
            dp.UpdateInitializeScript();

If you want to use DialogPage for this, you should be subclassing it in your page.  If you just instantiate it, it will be disconnected from the current HttpRequest and won't write anything to the browser.

I tried window.parent.waWindow.myDialog.Close();

myDialog is the querystring value. Added that in onlick on html button. That didn't close the dialog.

<input id="Button1" type="button" value="Close" onclick="window.parent.waWindow.myDialog.Close();" />

This is what I am using to open the window -

<ActionDefinition ID="LFRouterMD">
        <Title>MD-Router</Title>
        <Action>
            <![CDATA[
            var selectObj =         context.getSelectedItems("ENTRIES");
            var selectedEntries = selectObj.items;
            var entry = selectedEntries[0];
        
            var dobj = waWindow.getAvailableDlg(); 
            dobj.OpenDialog("Router.aspx?docID=" +         entry.id, 600, 700, true);
            dobj.onclose = function() {
                metadataControl.refresh();
            }
            ]]>
        </Action>
        <Enabled>
            <![CDATA[
            return true;
            ]]> 
        </Enabled>
        <IconClass>LFRouterIcon</IconClass>
        <Toolbars>3</Toolbars>
</ActionDefinition >

Was there an error in the console?  What do you see if you step through the code with a debugger?