diff --git a/src/silx/gui/plot/tools/profile/manager.py b/src/silx/gui/plot/tools/profile/manager.py
index 6f4ba358ef..8ed2eae981 100644
--- a/src/silx/gui/plot/tools/profile/manager.py
+++ b/src/silx/gui/plot/tools/profile/manager.py
@@ -1055,9 +1055,11 @@ def initProfileWindow(self, profileWindow, roi):
 
         # Trick to avoid blinking while retrieving the right window size
         # Display the window, hide it and wait for some event loops
+        eventLoop = qt.QEventLoop(self)
         profileWindow.show()
+        # Handle PyQt 5.15. Fix issue #4135 
+        eventLoop.processEvents()
         profileWindow.hide()
-        eventLoop = qt.QEventLoop(self)
         for _ in range(10):
             if not eventLoop.processEvents():
                 break