Fix frame cursor functions ignoring stack

src/buffer.rs

@@ -184,7 +184,7 @@ impl Buffer {
     }
 
     /// Ignores the stack.
-    pub(crate) fn at(&self, x: u16, y: u16) -> &Cell {
+    pub fn at(&self, x: u16, y: u16) -> &Cell {
         assert!(x < self.size.width);
         assert!(y < self.size.height);
         let i = self.index(x, y);
@@ -208,6 +208,14 @@ impl Buffer {
         self.stack.pop();
     }
 
+    pub fn local_to_global(&self, pos: Pos) -> Pos {
+        pos + self.stack.last().map(|(p, _)| *p).unwrap_or(Pos::ZERO)
+    }
+
+    pub fn global_to_local(&self, pos: Pos) -> Pos {
+        pos - self.stack.last().map(|(p, _)| *p).unwrap_or(Pos::ZERO)
+    }
+
     fn drawable_area(&self) -> (Pos, Size) {
         self.stack.last().copied().unwrap_or((Pos::ZERO, self.size))
     }

src/frame.rs

@@ -44,11 +44,11 @@ impl Frame {
     }
 
     pub fn cursor(&self) -> Option<Pos> {
-        self.cursor
+        self.cursor.map(|p| self.buffer.global_to_local(p))
     }
 
     pub fn set_cursor(&mut self, pos: Option<Pos>) {
-        self.cursor = pos;
+        self.cursor = pos.map(|p| self.buffer.local_to_global(p));
     }
 
     pub fn show_cursor(&mut self, pos: Pos) {