tools (common/template_xmlui: add multi and value propertied to OptionsWidget

sat/tools/common/template_xmlui.py

@@ -89,6 +89,14 @@ class OptionsWidget(Widget):
         for value, label in self.items:
             yield value
 
+    @property
+    def value(self):
+        if self.multi or self.no_select or len(self.selected) != 1:
+            raise ValueError(
+                "Can't get value for list with multiple selections or nothing selected"
+            )
+        return self.selected[0]
+
     @property
     def labels(self):
         """return only labels from self.items"""
@@ -111,6 +119,10 @@ class OptionsWidget(Widget):
     def no_select(self):
         return "noselect" in self.style
 
+    @property
+    def multi(self):
+        return "multi" in self.style
+
 
 class EmptyWidget(xmlui.EmptyWidget, Widget):
     def __init__(self, _xmlui_parent):