test: Use synthetic events to click on #logout

There is something unknown going on that makes using a real mouse
click unreliable.  Maybe the menu is being animated and the click
misses the menu item while it is flying around, or maybe something
else. We don't want to test the menu here, we just want to log out.

test/common/testlib.py

@@ -519,6 +519,7 @@ class Browser:
         altKey: bool = False,
         metaKey: bool = False,
         scrollVisible: bool = True,
+        synthetic: bool = False,
     ) -> None:
         """Do a mouse event in the browser.
 
@@ -538,7 +539,13 @@ class Browser:
 
         # TODO: x and y are not currently implemented: webdriver (0, 0) is the element's center, not top left corner
         # in these cases, use the old MouseEvent emulation
-        if x is not None or y is not None or (self.browser == "chromium" and self.chromium_fake_mouse):
+        if x is not None or y is not None:
+            synthetic = True
+
+        if self.browser == "chromium" and self.chromium_fake_mouse:
+            synthetic = True
+
+        if synthetic:
             self.call_js_func('ph_mouse', selector, event, x or 0, y or 0, btn, ctrlKey, shiftKey, altKey, metaKey)
             return
 
@@ -1092,9 +1099,9 @@ class Browser:
             # happens when cockpit is still running
             self.open_session_menu()
             try:
-                # HACK: scrolling into view sometimes triggers TopNav's handleClickOutside() hack
-                # we don't need it here, if the session menu is visible then so is the dropdown
-                self.mouse('#logout', "click", scrollVisible=False)
+                # HACK: real events seem to get lost occasionally, so
+                # let's use the more reliable synthetic ones.
+                self.mouse('#logout', "click", synthetic=True)
             except RuntimeError as e:
                 # logging out does destroy the current frame context, it races with the driver finishing the command
                 if "Execution context was destroyed" not in str(e):