I am using darktable-2.7.0+2162_g60067f3d9-win64.exe. I think because I pressed a wrong shortcut key, the lighttable and darkroom buttons disappeared from the top, right corner of darkroom. In addition, whenever I open darkroom now, the side panels, the top panel, and the bottom panel do not appear, and I have to click on the arrowheads to make them appear.