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).
Eat & Live Well! A different response: One cup of fresh green beans with a bit of water takes about 3-4 minutes to cook in a microwave oven. Increase time by about 2 minutes for each cup of beans, checking frequently for done-ness. Canned green beans only need about 2 minutes to warm 2 cups with a bit of liquid.