A filling method for filling a reservoir of variable working volume with a fluid, the method being characterized in that the reservoir is firstly emptied of any content, such that its working volume is substantially zero, and the fluid is then injected into the reservoir, thereby increasing the working volume of the reservoir. A flexi circuit, or the equivalent, is attached to the block and is printed with generally c-shaped conductive strips, which form connections at open parts of the feed lines, in such a manner that movement of the block will cause changes in the effective lengths of the feed lines and hence the relative phases of antennas fed by those feed lines. The VMM is further provided with a switching module, which alters a state of a VM based on a command for switching the VM, saves a graphics card state before the VM is switched to the background and restores the stored graphics card state to the graphics card when the VM is switched back to the foreground.