fix: aim toasts at the sheet they answer from

src/telephony/client/ui/main_window.py

@@ -394,10 +394,13 @@ def _refresh_calling_controls(self, *args):
     def _toast_target(self):
         """Return the overlay of the topmost surface.
 
-        A presented dialog is painted above the window content, so a
-        toast raised on the window's own overlay would sit hidden
-        underneath an open sheet.
+        An open sheet and a presented dialog are both painted above
+        the window content, so a toast raised on the window's own
+        overlay would sit hidden underneath them.
         """
+        if self.sheet_host.get_open() and self.sheet_toast_overlay is not None:
+            return self.sheet_toast_overlay
+
         dialog = self.get_visible_dialog()
         if dialog is not None:
             overlay = self._find_toast_overlay(dialog.get_child())

src/telephony/client/ui/widgets/common_widget.py

@@ -53,12 +53,23 @@ def install_sheet_host(window):
     host.set_modal(True)
     host.set_content(content)
     window.set_content(host)
+    window.sheet_toast_overlay = None
     return host
 
 
 def present_sheet(window, child):
-    """Show a widget as the window's bottom sheet."""
-    window.sheet_host.set_sheet(child)
+    """Show a widget as the window's bottom sheet.
+
+    The sheet content rides inside its own toast overlay, because the
+    window's overlay sits under the sheet and a toast raised there
+    while a sheet is open answers to nobody. The host itself is left
+    where it is; the sheet slot is just a widget and takes the wrapper
+    without complaint.
+    """
+    overlay = Adw.ToastOverlay()
+    overlay.set_child(child)
+    window.sheet_toast_overlay = overlay
+    window.sheet_host.set_sheet(overlay)
     window.sheet_host.set_open(True)