WPF: Grid like uniformgrid with variable row/col sizes: Does it exist?

I'm looking for a grid control that works like UniformGrid, except that it should have dynamically sized cell sizes (as you probably know, uniformgrid keeps all row heights equal and all column widths equal). Does this exist at all?

UniformGrid works fine for some purposes (when controls are roughly the same size, so it开发者_如何学C won't look like 90% empty space), but when I want a simple two-column layout (for instance when laying out field labels and field text boxes in a dialog) without having to specify grid column and grid row for each and every control, this would be very practical.

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I've written a custom panel that does "form layout" (groups of two columns, all labels same size, all control same size,everything aligned, etc.). It's on my blog.