When used on a device with HTC dialer, the dialer itself is also TopMost and reactivates itself every second or so. This causes the CallerUtility, which is TopMost as well, to go to the background. This patch adds a timer which re-activates the window every 250ms causing it to stay on top of the HTC dialer. However, some flickering is present (htc dialer reactivates, within 250ms callerutility reactivates as well and gets back on top).
An additional solution might be to remove the topmost flag from the HTC Dialer dialog using p/invoke. However I've not looked into this further as the current solution makes it workable. Removing topmost from the HTC Dialer may also cause other unwanted effects (such as a game popping back over the dialer making it impossible to accept a call, or so (just a thought)).
ShowWindow timer patch