score:-1

may be this will help you...

how can i get all controls from a form including controls in any container?

once you have the list you can query'em

score:3

something like this should work (not perfect code by any means...just meant to get the idea across):

public ienumerable<control> getselfandchildrenrecursive(control parent)
{
    list<control> controls = new list<control>();

    foreach(control child in parent.controls)
    {
        controls.addrange(getselfandchildrenrecursive(child));
    }

    controls.add(parent);

    return controls;
}

var result = getselfandchildrenrecursive(toplevelcontrol)
    .where(c => c is textbox || c is checkbox);

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