macOS: fix window cascading

macos/GhosttyUITests/GhosttyWindowPositionUITests.swift

@@ -10,6 +10,61 @@ import XCTest
 final class GhosttyWindowPositionUITests: GhosttyCustomConfigCase {
     override static var runsForEachTargetApplicationUIConfiguration: Bool { false }
 
+    // MARK: - Cascading
+
+    @MainActor func testWindowCascading() async throws {
+        try updateConfig(
+            """
+            title = "GhosttyWindowPositionUITests"
+            """
+        )
+
+        let app = try ghosttyApplication()
+        // Suppress Restoration
+        app.launchArguments += ["-NSQuitAlwaysKeepsWindows", "NO"]
+        // Clean run
+        app.launchEnvironment["GHOSTTY_CLEAR_USER_DEFAULTS"] = "YES"
+
+        app.launch() // window in the center
+
+//        app.menuBarItems["Window"].firstMatch.click()
+//        app.menuItems["_zoomTopLeft:"].firstMatch.click()
+//
+//        // wait for the animation to finish
+//        try await Task.sleep(for: .seconds(0.5))
+
+        let window = app.windows.firstMatch
+        let windowFrame = window.frame
+//        XCTAssertEqual(windowFrame.minX, 0, "Window should be on the left")
+
+        app.typeKey("n", modifierFlags: [.command])
+
+        let window2 = app.windows.firstMatch
+        XCTAssertTrue(window2.waitForExistence(timeout: 5), "New window should appear")
+        let windowFrame2 = window2.frame
+        XCTAssertNotEqual(windowFrame, windowFrame2, "New window should have moved")
+
+        XCTAssertEqual(windowFrame2.minX, windowFrame.minX + 30, accuracy: 5, "New window should be on the right")
+
+        app.typeKey("n", modifierFlags: [.command])
+
+        let window3 = app.windows.firstMatch
+        XCTAssertTrue(window3.waitForExistence(timeout: 5), "New window should appear")
+        let windowFrame3 = window3.frame
+        XCTAssertNotEqual(windowFrame2, windowFrame3, "New window should have moved")
+
+        XCTAssertEqual(windowFrame3.minX, windowFrame2.minX + 30, accuracy: 5, "New window should be on the right")
+
+        app.typeKey("n", modifierFlags: [.command])
+
+        let window4 = app.windows.firstMatch
+        XCTAssertTrue(window4.waitForExistence(timeout: 5), "New window should appear")
+        let windowFrame4 = window4.frame
+        XCTAssertNotEqual(windowFrame3, windowFrame4, "New window should have moved")
+
+        XCTAssertEqual(windowFrame4.minX, windowFrame3.minX + 30, accuracy: 5, "New window should be on the right")
+    }
+
     // MARK: - Restore round-trip per titlebar style
 
     @MainActor func testRestoredNative() throws { try runRestoreTest(titlebarStyle: "native") }

macos/Sources/Features/Terminal/TerminalController.swift

@@ -200,7 +200,9 @@ class TerminalController: BaseTerminalController, TabGroupCloseCoordinator.Contr
         if all.count > 1 {
             lastCascadePoint = window.cascadeTopLeft(from: lastCascadePoint)
         } else {
-            lastCascadePoint = window.cascadeTopLeft(from: NSPoint(x: window.frame.minX, y: window.frame.maxY))
+            // We assume the window frame is already correct at this point,
+            // so we pass .zero to let cascade use the current frame position.
+            lastCascadePoint = window.cascadeTopLeft(from: .zero)
         }
     }
 
@@ -256,6 +258,8 @@ class TerminalController: BaseTerminalController, TabGroupCloseCoordinator.Contr
         // take effect. Our best theory is there is some next-event-loop-tick logic
         // that Cocoa is doing that we need to be after.
         DispatchQueue.main.async {
+            c.showWindow(self)
+
             // Only cascade if we aren't fullscreen.
             if let window = c.window {
                 if !window.styleMask.contains(.fullScreen) {
@@ -264,8 +268,6 @@ class TerminalController: BaseTerminalController, TabGroupCloseCoordinator.Contr
                 }
             }
 
-            c.showWindow(self)
-
             // All new_window actions force our app to be active, so that the new
             // window is focused and visible.
             NSApp.activate(ignoringOtherApps: true)