can load partial params files

dstat_interface/params.py

@@ -70,12 +70,11 @@ def load_params(window, path):
 
 def set_params(window, params):
     window.adc_pot.params = params
-
-    if not 'experiment_index' in params:
-        logger.warning("Missing experiment parameters.")
-        return
-    window.expcombobox.set_active(
-                    window.exp_window.classes[params['experiment_index']][0])
+    if 'experiment_index' in params:
+        window.expcombobox.set_active(
+            window.exp_window.classes[params['experiment_index']][0]
+            )
+                            
     window.exp_window.set_params(params['experiment_index'], params)
     window.analysis_opt_window.params = params
     window.db_window.params = params