macos: add float on top feature for terminal windows (#7237)

Closes #5188

**See:** 

-
https://github.com/ghostty-org/ghostty/discussions/5188#discussioncomment-12607781
-
https://github.com/ghostty-org/ghostty/discussions/5188#discussioncomment-12984898

macos/Sources/App/macOS/AppDelegate.swift

@@ -52,6 +52,8 @@ class AppDelegate: NSObject,
     @IBOutlet private var menuSelectSplitLeft: NSMenuItem?
     @IBOutlet private var menuSelectSplitRight: NSMenuItem?
     @IBOutlet private var menuReturnToDefaultSize: NSMenuItem?
+    @IBOutlet private var menuFloatOnTop: NSMenuItem?
+    @IBOutlet private var menuUseAsDefault: NSMenuItem?
 
     @IBOutlet private var menuIncreaseFontSize: NSMenuItem?
     @IBOutlet private var menuDecreaseFontSize: NSMenuItem?
@@ -175,6 +177,12 @@ class AppDelegate: NSObject,
             handler: localEventHandler)
 
         // Notifications
+        NotificationCenter.default.addObserver(
+            self,
+            selector: #selector(windowDidBecomeKey),
+            name: NSWindow.didBecomeKeyNotification,
+            object: nil
+        )
         NotificationCenter.default.addObserver(
             self,
             selector: #selector(quickTerminalDidChangeVisibility),
@@ -497,6 +505,16 @@ class AppDelegate: NSObject,
         return event
     }
 
+    @objc private func windowDidBecomeKey(_ notification: Notification) {
+        guard let terminal = notification.object as? TerminalWindow else {
+            // If some other window became key we always turn this off
+            self.menuFloatOnTop?.state = .off
+            return
+        }
+        
+        self.menuFloatOnTop?.state = terminal.level == .floating ? .on : .off
+    }
+
     @objc private func quickTerminalDidChangeVisibility(_ notification: Notification) {
         guard let quickController = notification.object as? QuickTerminalController else { return }
         self.menuQuickTerminal?.state = if (quickController.visible) { .on } else { .off }
@@ -844,6 +862,22 @@ class AppDelegate: NSObject,
         hiddenState = nil
     }
 
+    @IBAction func floatOnTop(_ menuItem: NSMenuItem) {
+        menuItem.state = menuItem.state == .on ? .off : .on
+        guard let window = NSApp.keyWindow else { return }
+        window.level = menuItem.state == .on ? .floating : .normal
+    }
+
+    @IBAction func useAsDefault(_ sender: NSMenuItem) {
+        let ud = UserDefaults.standard
+        let key = TerminalWindow.defaultLevelKey
+        if (menuFloatOnTop?.state == .on) {
+            ud.set(NSWindow.Level.floating, forKey: key)
+        } else {
+            ud.removeObject(forKey: key)
+        }
+    }
+
     @IBAction func bringAllToFront(_ sender: Any) {
         if !NSApp.isActive {
             NSApp.activate(ignoringOtherApps: true)
@@ -899,3 +933,20 @@ class AppDelegate: NSObject,
         }
     }
 }
+
+// MARK: NSMenuItemValidation
+
+extension AppDelegate: NSMenuItemValidation {
+    func validateMenuItem(_ item: NSMenuItem) -> Bool {
+        switch item.action {
+        case #selector(floatOnTop(_:)),
+            #selector(useAsDefault(_:)):
+            // Float on top items only active if the key window is a primary
+            // terminal window (not quick terminal).
+            return NSApp.keyWindow is TerminalWindow
+
+        default:
+            return true
+        }
+    }
+}

macos/Sources/App/macOS/MainMenu.xib

@@ -25,6 +25,7 @@
                 <outlet property="menuCopy" destination="Jqf-pv-Zcu" id="bKd-1C-oy9"/>
                 <outlet property="menuDecreaseFontSize" destination="kzb-SZ-dOA" id="Y1B-Vh-6Z2"/>
                 <outlet property="menuEqualizeSplits" destination="3gH-VD-vL9" id="SiZ-ce-FOF"/>
+                <outlet property="menuFloatOnTop" destination="uRj-7z-1Nh" id="94n-o9-Jol"/>
                 <outlet property="menuIncreaseFontSize" destination="CIH-ey-Z6x" id="hkc-9C-80E"/>
                 <outlet property="menuMoveSplitDividerDown" destination="Zj7-2W-fdF" id="997-LL-nlN"/>
                 <outlet property="menuMoveSplitDividerLeft" destination="wSR-ny-j1a" id="HCZ-CI-2ob"/>
@@ -56,6 +57,7 @@
                 <outlet property="menuTerminalInspector" destination="QwP-M5-fvh" id="wJi-Dh-S9f"/>
                 <outlet property="menuToggleFullScreen" destination="8kY-Pi-KaY" id="yQg-6V-OO6"/>
                 <outlet property="menuToggleVisibility" destination="DOX-wA-ilh" id="iBj-Bc-2bq"/>
+                <outlet property="menuUseAsDefault" destination="TrB-O8-g8H" id="af4-Jh-2HU"/>
                 <outlet property="menuZoomSplit" destination="oPd-mn-IEH" id="wTu-jK-egI"/>
             </connections>
         </customObject>
@@ -402,6 +404,19 @@
                                     <action selector="returnToDefaultSize:" target="-1" id="Bpt-GO-UU1"/>
                                 </connections>
                             </menuItem>
+                            <menuItem isSeparatorItem="YES" id="Cm3-gn-vtj"/>
+                            <menuItem title="Float on Top" id="uRj-7z-1Nh">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <connections>
+                                    <action selector="floatOnTop:" target="bbz-4X-AYv" id="N58-PO-7pj"/>
+                                </connections>
+                            </menuItem>
+                            <menuItem title="Use as Default" id="TrB-O8-g8H">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <connections>
+                                    <action selector="useAsDefault:" target="bbz-4X-AYv" id="RHA-Nl-L2U"/>
+                                </connections>
+                            </menuItem>
                             <menuItem isSeparatorItem="YES" id="CpM-rI-Sc1"/>
                             <menuItem title="Bring All to Front" id="LE2-aR-0XJ">
                                 <modifierMask key="keyEquivalentModifierMask"/>

macos/Sources/Features/Terminal/TerminalWindow.swift

@@ -1,6 +1,9 @@
 import Cocoa
 
 class TerminalWindow: NSWindow {
+    /// This is the key in UserDefaults to use for the default `level` value.
+    static let defaultLevelKey: String = "TerminalDefaultLevel"
+
     @objc dynamic var keyEquivalent: String = ""
 
     /// This is used to determine if certain elements should be drawn light or dark and should
@@ -63,6 +66,8 @@ class TerminalWindow: NSWindow {
 		if titlebarTabs {
 			generateToolbar()
 		}
+        
+        level = UserDefaults.standard.value(forKey: Self.defaultLevelKey) as? NSWindow.Level ?? .normal
     }
 
     deinit {