include uninstaller.

installer_script/installer.nsi

@@ -5,18 +5,38 @@ RequestExecutionLevel user
 
 SetDatablockOptimize on
 SetCompress auto
-SetCompressor /FINAL /SOLID lzma
+SetCompressor /SOLID lzma
 
 Name "obs-multi-rtmp"
 Caption "Multiple RTMP Output Plugin for OBS Studio"
 Icon "${NSISDIR}\Contrib\Graphics\Icons\win-install.ico"
 
+Var /Global DefInstDir
 Function .onInit
     ReadEnvStr $0 "ALLUSERSPROFILE"
-    StrCpy $INSTDIR "$0\obs-studio\plugins\obs-multi-rtmp"
+    StrCpy $DefInstDir "$0\obs-studio\plugins\obs-multi-rtmp"
+    StrCpy $INSTDIR "$DefInstDir"
+
+    IfFileExists "$DefInstDir\*.*" AskUninst DontAskUninst
+    AskUninst:
+        MessageBox MB_YESNO|MB_ICONQUESTION "Uninstall obs-multi-rtmp?" IDYES DoUninst IDNO NotDoUninst
+    DoUninst:
+        RMDir /r "$DefInstDir"
+        MessageBox MB_OK|MB_ICONINFORMATION "Done."
+        Quit
+    NotDoUninst:
+    DontAskUninst:
 FunctionEnd
 
-Page directory
+Function onDirPageLeave
+StrCmp "$INSTDIR" "$DefInstDir" DirNotModified DirModified
+DirModified:
+MessageBox MB_OK|MB_ICONSTOP "Please don't change the install directory."
+Abort
+DirNotModified:
+FunctionEnd
+
+Page directory "" "" onDirPageLeave
 Page instfiles
 
 Section