Windows are surrounded by a frame with a titlebar at the top next to a small box. The frame is a grey colour for all windows except that which has the input focus, where it is black.
In the default configuration, lwm uses the enter-to-focus scheme, where moving the pointer into a window gives that window the input focus. Lwm may also be configured to use the click-to-focus scheme, where a window must be clicked on (with any button) to receive the input focus. Clicking on a window in this mode causes the window to be raised. Note that a click used to focus a window is always swallowed by lwm, so clicking a button in a new window requires two clicks.
A button 1 click on a window frame brings that window to the top. Dragging button 1 on the frame of a resizable window repositions that edge of the window. If a corner rather than an edge is dragged, then both edges forming the corner are repositioned. While you're reshaping a window, a little window pops up to show you the window's current size.
In the default configuration, button 1 on the root window does nothing.
Button 2 is used to drag a window by its frame, repositioning the window but maintaining its position in the window stack.
In the default configuration, button 2 on the root window brings up a new shell.
A button 3 click on a window frame hides that window. Pressing button 3 on the root window brings up a menu. The various items unhide the named hidden window.
A button 3 click in the frame while Shift is held down pushes the window to the back, under any other windows. (Users with 4-button mice are encouraged to use their fourth button for this function.)
A click with any button inside the little white box in a window's frame can be used to close the window.