Qt: Re-enable menu keyboard navigation and mnemonics

when "Keyboard requries capture" is enabled and mouse isn't captured
on Windows and Linux

src/qt/qt_main.cpp

@@ -585,7 +585,11 @@ main(int argc, char *argv[])
     }
 
     if (!vmm_enabled)
+#ifdef Q_OS_MACOS
         qt_set_sequence_auto_mnemonic(false);
+#else
+        qt_set_sequence_auto_mnemonic(!!kbd_req_capture);
+#endif
     app.setStyle(new StyleOverride());
 
     bool startMaximized = window_remember && monitor_settings[0].mon_window_maximized;

src/qt/qt_mainwindow.cpp

@@ -92,6 +92,8 @@ extern bool cpu_thread_running;
 #    include <QVulkanFunctions>
 #endif
 
+void qt_set_sequence_auto_mnemonic(bool b);
+
 #include <array>
 #include <memory>
 #include <unordered_map>
@@ -335,6 +337,16 @@ MainWindow::MainWindow(QWidget *parent)
             }
             ui->stackedWidget->unsetCursor();
         }
+#ifndef Q_OS_MACOS
+        if (kbd_req_capture) {
+            qt_set_sequence_auto_mnemonic(!mouse_capture);
+            /* Hack to get the menubar to update the internal Alt+shortcut table */
+            if (!video_fullscreen) {
+                ui->menubar->hide();
+                ui->menubar->show();
+            }
+        }
+#endif
     });
 
     connect(qApp, &QGuiApplication::applicationStateChanged, [this](Qt::ApplicationState state) {
@@ -1034,6 +1046,14 @@ void
 MainWindow::on_actionKeyboard_requires_capture_triggered()
 {
     kbd_req_capture ^= 1;
+#ifndef Q_OS_MACOS
+    qt_set_sequence_auto_mnemonic(!!kbd_req_capture);
+    /* Hack to get the menubar to update the internal Alt+shortcut table */
+    if (!video_fullscreen) {
+        ui->menubar->hide();
+        ui->menubar->show();
+    }
+#endif
 }
 
 void
@@ -1432,7 +1452,7 @@ MainWindow::eventFilter(QObject *receiver, QEvent *event)
 	}
 	
 
-    if (!dopause) {
+    if (!dopause && (!kbd_req_capture || mouse_capture)) {
         if (event->type() == QEvent::Shortcut) {
             auto shortcutEvent = (QShortcutEvent *) event;
             if (shortcutEvent->key() == ui->actionExit->shortcut()) {

src/qt/qt_mainwindow.hpp

@@ -85,7 +85,7 @@ private slots:
     void on_actionCtrl_Alt_Esc_triggered();
     void on_actionHard_Reset_triggered();
     void on_actionRight_CTRL_is_left_ALT_triggered();
-    static void on_actionKeyboard_requires_capture_triggered();
+    void on_actionKeyboard_requires_capture_triggered();
     void on_actionResizable_window_triggered(bool checked);
     void on_actionInverted_VGA_monitor_triggered();
     void on_action0_5x_triggered();

src/qt/qt_styleoverride.cpp

@@ -24,6 +24,7 @@
 
 extern "C" {
 #include <86box/86box.h>
+#include <86box/plat.h>
 }
 
 #ifdef Q_OS_WINDOWS
@@ -41,7 +42,7 @@ StyleOverride::styleHint(
     QStyleHintReturn   *returnData) const
 {
     /* Disable using menu with alt key */
-    if (!vmm_enabled && (hint == QStyle::SH_MenuBar_AltKeyNavigation))
+    if (!vmm_enabled && (!kbd_req_capture || mouse_capture) && (hint == QStyle::SH_MenuBar_AltKeyNavigation))
         return 0;
 
     return QProxyStyle::styleHint(hint, option, widget, returnData);