Some ArcROI handlers use a none symbol instead of hidding the handler
Noticed with the ArcRoi.

In translation mode, if you hover the start of end handler (which are not visible) the mouse cursor change to a hand pointer.

The ROI also have to be the active one.
diff --git a/src/silx/gui/plot/items/_arc_roi.py b/src/silx/gui/plot/items/_arc_roi.py
index 8639998be..100bf85bc 100644
--- a/src/silx/gui/plot/items/_arc_roi.py
+++ b/src/silx/gui/plot/items/_arc_roi.py
@@ -265,22 +265,28 @@ class ArcROI(HandleBasedROI, items.LineMixIn, InteractionModeMixIn):
         :param RoiInteractionMode modeId:
         """
         if modeId is self.ThreePointMode:
+            self._handleStart.setVisible(True)
+            self._handleEnd.setVisible(True)
+            self._handleWeight.setVisible(True)
             self._handleStart.setSymbol("s")
             self._handleMid.setSymbol("s")
             self._handleEnd.setSymbol("s")
             self._handleWeight.setSymbol("d")
             self._handleMove.setSymbol("+")
         elif modeId is self.PolarMode:
+            self._handleStart.setVisible(True)
+            self._handleEnd.setVisible(True)
+            self._handleWeight.setVisible(True)
             self._handleStart.setSymbol("o")
             self._handleMid.setSymbol("o")
             self._handleEnd.setSymbol("o")
             self._handleWeight.setSymbol("d")
             self._handleMove.setSymbol("+")
         elif modeId is self.MoveMode:
-            self._handleStart.setSymbol("")
+            self._handleStart.setVisible(False)
+            self._handleEnd.setVisible(False)
+            self._handleWeight.setVisible(False)
             self._handleMid.setSymbol("+")
-            self._handleEnd.setSymbol("")
-            self._handleWeight.setSymbol("")
             self._handleMove.setSymbol("+")
         else:
             assert False
['src/silx/gui/plot/items/_arc_roi.py']