Home PostMessage for all instances of a specific form (ClassName):
 In a VCL Forms program, I have a Form that implements a method for handling windows messages and updating some controls on the Form, something like: procedure OnMsgTest (var Msg: TMessage); message WM_CUSTOMTEST;  I use PostMessage with a custom message to this Form, using a code like this:  h := FindWindow('TFrmTest', nil); if IsWindow(h) then begin PostMessage(h, WM_CUSTOMTEST, 0, 0); end;  When the Form is instantiated several times, using the above code to send the message, only one Form instance updates the information on the screen. I would like all open and instantiated Forms to receive the message. An important note: PostMessage can occur within the Form process itself, but also from another process. So, I believe a loop through the Forms would not work. What would be the best approach to reach my goal?