Use the keyboardFocusPolicy resource to specify how a window becomes active and receives keyboard input. The default value for this resource is explicit, which moves the keyboard input into a new window only when the window is explicitly selected. Keyboard input goes to the selected window regardless of the location of the pointer until you select another window for keyboard input. The default focus-selection action is pressing Button 1 in a window. Explicit focus policy is also known as "click-to-type."
The other input focus policy is called pointer. Under this policy, keyboard input is always sent to the window that currently contains the mouse pointer. To change the default input focus policy, use the following specification in your .Xdefaults file:
Mwm*keyboardFocusPolicy: pointer
When the focus policy is set to pointer, the window with the input focus will not automatically be raised to the top of the stack.
The focusAutoRaise resource determines whether the window with input focus is raised. This resource has a default value of True when the keyboard focus is explicit, and a default value of False when the keyboard focus is pointer. If you are using pointer policy and you want the window with input focus to automatically be raised to the top of the stack, use the following specification:
Mwm*focusAutoRaise: True
To avoid flickering in the display while the pointer moves across a number of stacked windows, there is a brief delay before the window with the input focus is raised to the top of the stack. This delay is controlled by the autoRaiseDelay resource. The default is 500 milliseconds.