Components overlapping with form designer

I'm trying to create an application in C# using the forms designer in Visual Studio 2008. Coming from Java, it's a welcome relief not to have to hand code the whole layout, but there's something that doesn't seem to be working. The 'Dock' setting for components. I have a split pane, inside each pane of which are two more split panes. Whenever I set the main split pain to dock horizontally and vertically (the middle button in the designer), it underlaps the toolbar, and the same happens in the sub-panes - they overlap the drop down box I've set to dock at the top.

Is it best to have just one docking component per panel or is there a way around this? The window looks fine at the default size, but once it's resized nothing changes size to fit.

The code from the designer is at http://mi6.nu/FrmMain.Designer.resx if anyone could take a look and see if I'm doing something wrong. It's probably something simple, but maybe someone else has had a similar problem.

Thanks.