Viewer: Fix mouse wheel not working while selection bar is visible

Fixes #1898413 [Viewer: some mouse actions with popup bar displayed should be changed](https://bugs.launchpad.net/calibre/+bug/1898413)

src/pyj/read_book/iframe.pyj

@@ -137,7 +137,7 @@ class IframeBoss:
             'scroll_to_ref': self.on_scroll_to_ref,
             'set_reference_mode': self.set_reference_mode,
             'toggle_autoscroll': self.toggle_autoscroll,
-            'wheel_from_margin': self.wheel_from_margin,
+            'fake_wheel_event': self.fake_wheel_event,
             'window_size': self.received_window_size,
             'overlay_visibility_changed': self.on_overlay_visibility_changed,
             'show_search_result': self.show_search_result,
@@ -305,7 +305,8 @@ class IframeBoss:
     def gesture_from_margin(self, data):
         self.handle_gesture(data.gesture)
 
-    def wheel_from_margin(self, data):
+    def fake_wheel_event(self, data):
+        # these are wheel events from margin or selection mode
         self.onwheel(data.evt)
 
     def report_human_scroll(self, scrolled_by_frac):

src/pyj/read_book/selection_bar.pyj

@@ -247,6 +247,7 @@ class SelectionBar:
         container.addEventListener('touchend', self.touchend_on_container, {'passive': False})
         container.addEventListener('touchcancel', self.touchend_on_container, {'passive': False})
         container.addEventListener('keydown', self.on_keydown, {'passive': False})
+        container.addEventListener('wheel', self.on_wheel, {'passive': False})
         container.setAttribute('tabindex', '0')
 
         self.dragging_handle = None
@@ -289,6 +290,8 @@ class SelectionBar:
         clear(bar_container)
         bar_container.style.maxWidth = 'min(50rem, 90vw)' if self.supports_css_min_max else '50rem'
         bar_container.style.backgroundColor = get_color("window-background")
+        notes_container = E.div()
+        notes_container.addEventListener('wheel', def(evt): evt.stopPropagation();, {'passive': True})
         for x in [
             E.div(style='height: 4ex; display: flex; align-items: center; padding: 5px; justify-content: center'),
 
@@ -296,7 +299,7 @@ class SelectionBar:
 
             E.div(
                 style='display: none; padding: 5px;',
-                E.div(),
+                notes_container,
             )
         ]:
             bar_container.appendChild(x)
@@ -545,6 +548,10 @@ class SelectionBar:
                     self.end_handle_drag()
                     return
 
+    def on_wheel(self, ev):
+        ev.stopPropagation(), ev.preventDefault()
+        self.view.send_wheel_event_to_iframe(ev, 'selection-mode')
+
     def on_keydown(self, ev):
         ev.stopPropagation(), ev.preventDefault()
         if ev.key is 'Escape':

src/pyj/read_book/view.pyj

@@ -389,10 +389,13 @@ class View:
 
     def on_margin_wheel(self, which, event):
         event.preventDefault()
-        evt = {}
+        self.send_wheel_event_to_iframe(event, f'margin-{which}')
+
+    def send_wheel_event_to_iframe(self, event, location):
+        evt = {'location': location}
         for attr in ('deltaX', 'deltaY', 'deltaMode', 'altKey', 'ctrlKey', 'shiftKey', 'metaKey'):
             evt[attr] = event[attr]
-        self.iframe_wrapper.send_message('wheel_from_margin', evt=evt)
+        self.iframe_wrapper.send_message('fake_wheel_event', evt=evt)
 
     def forward_gesture(self, gesture):
         self.iframe_wrapper.send_message('gesture_from_margin', gesture=gesture)