diff --git a/widgetry/src/event_ctx.rs b/widgetry/src/event_ctx.rs
index c90f344d7d..703e074d49 100644
--- a/widgetry/src/event_ctx.rs
+++ b/widgetry/src/event_ctx.rs
@@ -34,6 +34,7 @@ pub struct EventCtx<'a> {
     pub prerender: &'a Prerender,
     pub(crate) style: &'a mut Style,
     pub(crate) updates_requested: Vec<UpdateType>,
+    pub(crate) canvas_movement_called: bool,
 }
 
 impl<'a> EventCtx<'a> {
@@ -63,6 +64,7 @@ impl<'a> EventCtx<'a> {
     /// auto-pan at the edge of the screen, using arrow keys, etc) depend on options set. Returns
     /// true if the canvas moved at all.
     pub fn canvas_movement(&mut self) -> bool {
+        self.canvas_movement_called = true;
         let prev = (self.canvas.cam_x, self.canvas.cam_y, self.canvas.cam_zoom);
         self.updates_requested
             .extend(self.canvas.handle_event(&mut self.input));
@@ -82,6 +84,7 @@ impl<'a> EventCtx<'a> {
             prerender: self.prerender,
             style: self.style,
             updates_requested: vec![],
+            canvas_movement_called: false,
         };
         let result = cb(&mut tmp);
         self.updates_requested.extend(tmp.updates_requested);
@@ -269,6 +272,7 @@ impl<'a> LoadingScreen<'a> {
             prerender: self.prerender,
             style: &mut self.style,
             updates_requested: vec![],
+            canvas_movement_called: false,
         };
 
         let mut txt = Text::from(Line(&self.title).small_heading());
diff --git a/widgetry/src/runner.rs b/widgetry/src/runner.rs
index 060d951714..81b2b24c7f 100644
--- a/widgetry/src/runner.rs
+++ b/widgetry/src/runner.rs
@@ -107,12 +107,28 @@ impl<A: SharedAppState> State<A> {
                 prerender,
                 style: &mut self.style,
                 updates_requested: vec![],
+                canvas_movement_called: false,
             };
             let started = Instant::now();
             self.app.event(&mut ctx);
             if DEBUG_PERFORMANCE {
                 println!("- event() took {}s", elapsed_seconds(started));
             }
+
+            // If the user is dragging the canvas, but then another UI state interrupts things
+            // (like a panel popping up that blocks the canvas) and canvas_movement() isn't called
+            // for this event, then cancel the drag.
+            if ctx.canvas.drag_canvas_from.is_some() && !ctx.canvas_movement_called {
+                ctx.canvas.drag_canvas_from = None;
+                // TODO When the user releases the mouse button, it'll count as
+                // normal_left_click(). An example why this is a bug:
+                //
+                // 1) Start dragging the map in A/B Street's sandbox mode
+                // 2) Press escape, bringing up a menu
+                // 3) Release the mouse while hovering off of the panel
+                // This counts as clicking "off the panel" and closes it immediately.
+            }
+
             // TODO We should always do has_been_consumed, but various hacks prevent this from being
             // true. For now, just avoid the specific annoying redraw case when a KeyRelease event
             // is unused.
@@ -339,6 +355,7 @@ pub fn run<
         prerender: &prerender,
         style: &mut style,
         updates_requested: vec![],
+        canvas_movement_called: false,
     });
     timer.stop("setup app");
     let app = App {