[vdr] calling MainMenuAction() from an other plugin

Hello I want to show an special message on the screen. (with image, buttons,...) My idear was to write an second Plugin which have a MainMenuAction which shows the message on the OSD. The param will be set by a service which was called before I call

cPlugin *Plugin = cPluginManager::GetPlugin("myShowMessage"); if (Plugin) Plugin->MainMenuAction();

The problem is that I need to call this code from an background thread, so the called plugin can't handle the osd.

Mar 28 10:27:49 localhost vdr[7282]: ERROR: attempt to open OSD while it is already open - using dummy OSD! Mar 28 10:27:49 localhost vdr[7282]: ERROR: OSD opened without closing previous OSD!

Is there any possibility to call the Plugin with full osd support?