!insertmacro MUI_UNPAGE_INSTFILES
!insertmacro MUI_LANGUAGE "English"
+
+Function .onInit
+
+ ReadRegStr \$R0 HKLM \
+ "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\${PRODUCT_ID}" \
+ "UninstallString"
+ StrCmp \$R0 "" done
+
+ MessageBox MB_OKCANCEL|MB_ICONEXCLAMATION \
+ "${PROGRAM_NAME} is already installed. \$\\n\$\\nClick 'OK' to remove the \
+ previous version or 'Cancel' to cancel this upgrade." \
+ IDOK uninst
+ Abort
+
+ uninst:
+ ClearErrors
+ Exec \$INSTDIR\uninst.exe ;
+
+ done:
+
+FunctionEnd
+
+
Section "${PROGRAM_NAME}${PROGRAM_VERSION} (required)" SecMainProg
SectionIn RO
SetOutPath \$INSTDIR