Wood will expand and contract across the grain, and a wide panel made of solid wood could change width by a half of an inch, warping the door frame. By allowing the wood panel to float, it can expand and contract without damaging the door.
Put trimmed and cleaned green beans in the steamer basket, set over the boiling water, cover, and steam until tender to the bite, 3 to 5 minutes (depending, again, on how crisp or tender you like your green beans).
Add garlic and onions and cook for a minute. Then add green beans and cook for a minute until beans turn bright green. Add the chicken broth, chopped red pepper, salt, and black pepper. Turn heat to low and cover with a lid, leaving lid cracked to allow steam to escape. Cook for 20 to 30 minutes or until liquid evaporates and beans are fairly soft, yet still a bit crisp.