macOS: add mouse state tests for #11276

It will fail on 4e24adf71 and success after #11276

macos/GhosttyUITests/GhosttyMouseStateTests.swift

@@ -0,0 +1,53 @@
+//
+//  GhosttyMouseStateTests.swift
+//  Ghostty
+//
+//  Created by Lukas on 19.03.2026.
+//
+
+import XCTest
+
+final class GhosttyMouseStateTests: GhosttyCustomConfigCase {
+    override static var runsForEachTargetApplicationUIConfiguration: Bool { false }
+
+    // https://github.com/ghostty-org/ghostty/pull/11276
+    @MainActor func testSelectionFocusChange() async throws {
+        let app = XCUIApplication()
+        app.activate()
+        // Write dummy text to a temp file, cat it into the terminal, then clean up
+        let lines = (1...200).map { "Line \($0): The quick brown fox jumps over the lazy dog. Lorem ipsum dolor sit amet, consectetur adipiscing elit." }
+        let text = lines.joined(separator: "\n") + "\n"
+        let tmpFile = NSTemporaryDirectory() + "ghostty_test_dummy.txt"
+        try text.write(toFile: tmpFile, atomically: true, encoding: .utf8)
+        defer { try? FileManager.default.removeItem(atPath: tmpFile) }
+
+        app.typeText("cat \(tmpFile)\r")
+        app.menuItems["Command Palette"].firstMatch.click()
+
+        let finder = XCUIApplication(bundleIdentifier: "com.apple.finder")
+        finder.activate()
+
+        app.activate()
+
+        app.buttons
+            .containing(NSPredicate(format: "label CONTAINS[c] 'Clear Screen'"))
+            .firstMatch
+            .click()
+        let surface = app.groups["Terminal pane"]
+        surface
+            .coordinate(withNormalizedOffset: .zero)
+            .withOffset(.init(dx: 20, dy: 10))
+            .click()
+
+        surface
+            .coordinate(withNormalizedOffset: .zero)
+            .withOffset(.init(dx: 20, dy: surface.frame.height * 0.5))
+            .hover()
+
+        NSPasteboard.general.clearContents()
+        app.typeKey("c", modifierFlags: .command)
+
+        XCTAssertEqual(NSPasteboard.general.string(forType: .string), nil, "Moving mouse shouldn't select any texts")
+    }
+}
+