Wooden doors and windows tend to stick inside their frames in summer because they're swollen with the summer's humidity. If you've got a Microplane-style zester handy, a few quick swipes can scrape away the sticking.
Photo by tokyofoodcast.
The legend behind Microplane-brand zesters is that they were turned into kitchen tools by a woodworker tired of seeing his lemons and oranges get mangled in graters, who then realised that a fine-toothed rasp in his shop did a much better job of it. Knowing that, a blogger at the New York Times' Bitten blog ran his Microplane along part of a kitchen cabinet door, just enough so that a "thirty-second of an inch or so" was worn away and the door swung open and closed more gracefully.
After running the Microplane through the washer again, it was ready to return to culinary duty. If you're not fond of scraping along your small doors, consider using candle wax to keep doors and windows from sticking.
The Always-Useful Microplane [Bitten Blog]