The wait command is similar to the after command in that it is used to delay execution for a period specified in milliseconds. Unlike after, the event loop processing of the interpreter continues to dispatch events during the delay. For example, if you used wait to display a message window for a specified period, the window would display correctly if it were resized, or moved.
As a design choice, it is preferable to use the after command to execute code in the future than to use wait. This command is not part of the regular Tcl/Tk distribution; it has been added by Hume Integration Software.