added compatibility for MS-Windows

Lichtklavier.pro

@@ -7,11 +7,15 @@ CONFIG += c++11
 # You can make your code fail to compile if it uses deprecated APIs.
 # In order to do so, uncomment the following line.
 #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
-                                # ADDED BY L.Mewes 28.09.2021
+unix{                           # ADDED BY L.Mewes 28.09.2021
 DEFINES += __LINUX_ALSA__       # Defines the Midi-API that RtMidi will use. For Linux (also Raspbian) it will be ALSA
 LIBS += -lasound                # Includes Sound and Threading-Libraries
 LIBS += -lpthread               #
-                                #
+}
+win32{                          # ADDED BY L.MEWES 09.10.2021
+DEFINES += __WINDOWS_MM__       # Defines the Midi-APi that RtMidi will use. For Microsoft (R) Windows (TM) it will be "Windows-MM", only for test reasons
+LIBS += -lwinmm                 # Includes multimedia-library
+}
 
 SOURCES += \
     CircleElement.cpp \