Use the tweak is very simple: launch an application and made a swipe down starting from the top left of the display. The screen of the app will therefore be reduced in size, and you can then take advantage of a true multitasking. In any case, for any doubt, Mirmir includes a tutorial.
Multitasking mode appears at the top of the windows of each application a gray bar with the name of the app. This is useful for dragging the screens on the display and to show further options. The tweak also supports notes gesture (pinch) to increase / decrease the size of the individual windows.
Mirmir can still be configured to suit your preference. For example, you can choose the default orientation of the windows (horizontal or vertical) and their size, the method of activation of the tweak, the ability to hide the status bar, and more.
You can download Mirmir through the BigBoss repo in Cydia at a price of approximately € 3.60.