apprt/gtk: nested splits are good

src/apprt/gtk/Split.zig

@@ -87,6 +87,9 @@ pub fn init(
     // Update our children so that our GL area is properly
     // added to the paned.
     self.updateChildren();
+
+    // The new surface should always grab focus
+    surface.grabFocus();
 }
 
 /// Focus on first Surface that can be found in given position. If there's a
@@ -199,8 +202,19 @@ pub fn replace(
     // Update our paned children. This will reset the divider
     // position but we want to keep it in place so save and restore it.
     const pos = c.gtk_paned_get_position(self.paned);
-    self.updateChildren();
+    defer c.gtk_paned_set_position(self.paned, pos);
-    c.gtk_paned_set_position(self.paned, pos);
+
+    if (ptr == &self.top_left) {
+        c.gtk_paned_set_start_child(
+            @ptrCast(self.paned),
+            self.top_left.widget(),
+        );
+    } else {
+        c.gtk_paned_set_end_child(
+            @ptrCast(self.paned),
+            self.bottom_right.widget(),
+        );
+    }
 }
 
 /// Update the paned children to represent the current state.

src/apprt/gtk/Tab.zig

@@ -159,27 +159,6 @@ pub fn deinit(self: *Tab) void {
     }
 }
 
-/// Splits the current child surface into a Paned in given direction. Child of
-/// Tab must be a Surface.
-pub fn splitSurface(self: *Tab, direction: input.SplitDirection) !void {
-    assert(self.child == .surface);
-
-    const surface = switch (self.child) {
-        .surface => |s| s,
-        else => unreachable,
-    };
-    self.removeChild();
-
-    // Create a Paned with two Surfaces.
-    const paned = try Paned.create(self.window.app.core_app.alloc, surface, direction);
-
-    // Add Paned to the Tab.
-    self.setChild(.{ .paned = paned });
-
-    // Focus on new surface
-    paned.focusFirstSurfaceInPosition(.end);
-}
-
 /// Remove the current child from the Tab. Noop if no child set.
 pub fn removeChild(self: *Tab) void {
     const widget = self.child.widget() orelse return;