--- src/rmdPrefsWidget.py	2008-11-23 16:09:14.000000000 +0100
+++ src/rmdPrefsWidget.py.new	2010-05-24 16:23:30.255865721 +0200
@@ -302,9 +302,29 @@
     def remPort(self,lwi):
         self.jack_lsp_listSave.takeItem(self.jack_lsp_listSave.row(lwi))
 
+    def which(self,program):
+        import os
+        def is_exe(fpath):
+            return os.path.exists(fpath) and os.access(fpath, os.X_OK)
+
+        fpath, fname = os.path.split(program)
+        if fpath:
+            if is_exe(program):
+                return program
+        else:
+            for path in os.environ["PATH"].split(os.pathsep):
+                exe_file = os.path.join(path, program)
+                if is_exe(exe_file):
+                    return exe_file
+
+        return None
+
     def __runJackLSP__(self,button=None):
         self.ports=[]
         failed=0
+        if self.which('jack_lsp') == None:
+            self.jack_button.setEnabled(False)
+            return
         (stdin,stdout,stderr)=os.popen3(['jack_lsp'],'t')
         ports=stdout.readlines()
         stdin.close()