WindowServer: Remove misbehavior conditions for modals

This was too restrictive and there are already UI elements that rely
on this behavior. Now Blocking modals will preempt interaction with
all windows in their modal chain except those descending from them.
Fixes crashing in FilePicker when permission is denied.

Userland/Services/WindowServer/ConnectionFromClient.cpp

@@ -576,10 +576,6 @@ void ConnectionFromClient::create_window(i32 window_id, Gfx::IntRect const& rect
             did_misbehave("CreateWindow with bad parent_window_id");
             return;
         }
-        if ((parent_window->is_blocking() && mode != (i32)WindowMode::CaptureInput) || parent_window->is_capturing_input()) {
-            did_misbehave("CreateWindow with forbidden parent mode");
-            return;
-        }
     }
 
     if (type < 0 || type >= (i32)WindowType::_Count) {

Userland/Services/WindowServer/Window.cpp

@@ -442,7 +442,7 @@ void Window::event(Core::Event& event)
         return;
     }
 
-    if (blocking_modal_window() && !is_capturing_input()) {
+    if (blocking_modal_window()) {
         // We still want to handle the WindowDeactivated event below when a new modal is
         // created to notify its parent window, despite it being "blocked by modal window".
         if (event.type() != Event::WindowDeactivated)
@@ -660,6 +660,8 @@ bool Window::is_active() const
 Window* Window::blocking_modal_window()
 {
     auto maybe_blocker = WindowManager::the().for_each_window_in_modal_chain(*this, [&](auto& window) {
+        if (is_descendant_of(window))
+            return IterationDecision::Continue;
         if (window.is_blocking() && this != &window)
             return IterationDecision::Break;
         return IterationDecision::Continue;

Userland/Services/WindowServer/WindowManager.cpp

@@ -348,8 +348,7 @@ void WindowManager::move_to_front_and_make_active(Window& window)
         return IterationDecision::Continue;
     });
 
-    auto* blocker = window.blocking_modal_window();
-    if (blocker && !window.is_capturing_input()) {
+    if (auto* blocker = window.blocking_modal_window()) {
         blocker->window_stack().move_to_front(*blocker);
         set_active_window(blocker, true);
     } else {
@@ -1230,7 +1229,7 @@ void WindowManager::process_mouse_event_for_window(HitTestResult& result, MouseE
 
     // First check if we should initiate a move or resize (Super+LMB or Super+RMB).
     // In those cases, the event is swallowed by the window manager.
-    if ((!blocking_modal_window || window.is_capturing_input()) && window.is_movable()) {
+    if (!blocking_modal_window && window.is_movable()) {
         if (!window.is_fullscreen() && m_keyboard_modifiers == Mod_Super && event.type() == Event::MouseDown && event.button() == MouseButton::Primary) {
             start_window_move(window, event);
             return;
@@ -1248,7 +1247,7 @@ void WindowManager::process_mouse_event_for_window(HitTestResult& result, MouseE
             set_active_window(&window);
     }
 
-    if (blocking_modal_window && !window.is_capturing_input()) {
+    if (blocking_modal_window) {
         if (event.type() == Event::Type::MouseDown) {
             // We're clicking on something that's blocked by a modal window.
             // Flash the modal window to let the user know about it.
@@ -1835,8 +1834,7 @@ void WindowManager::notify_previous_active_input_window(Window& previous_input_w
 void WindowManager::set_active_window(Window* new_active_window, bool make_input)
 {
     if (new_active_window) {
-        auto* blocker = new_active_window->blocking_modal_window();
-        if (blocker && !new_active_window->is_capturing_input()) {
+        if (auto* blocker = new_active_window->blocking_modal_window()) {
             VERIFY(blocker->is_modal());
             VERIFY(blocker != new_active_window);
             new_active_window = blocker;

Userland/Services/WindowServer/WindowManager.h

@@ -241,24 +241,24 @@ public:
     template<typename Callback>
     Window* for_each_window_in_modal_chain(Window& window, Callback callback)
     {
-        Window* maybe_break = nullptr;
         Function<Window*(Window&)> recurse = [&](Window& w) -> Window* {
             if (!w.is_modal()) {
                 auto decision = callback(w);
                 if (decision == IterationDecision::Break)
-                    return maybe_break = &w;
+                    return &w;
             }
             for (auto& child : w.child_windows()) {
                 if (!child || child->is_destroyed() || !child->is_modal())
                     continue;
                 auto decision = callback(*child);
+                if (auto* result = recurse(*child))
+                    return result;
                 if (decision == IterationDecision::Break)
-                    return maybe_break = child;
-                recurse(*child);
+                    return child;
             }
-            return maybe_break;
+            return nullptr;
         };
-        if (auto* modeless = window.modeless_ancestor(); modeless)
+        if (auto* modeless = window.modeless_ancestor())
             return recurse(*modeless);
         return nullptr;
     }

Userland/Services/WindowServer/WindowMode.h

@@ -14,7 +14,7 @@ namespace WindowServer {
 // - Passive:       Joins the modal chain but has no modal effect (default mode for child windows)
 // - RenderAbove:   Renders above its parent
 // - CaptureInput:  Captures input from its parent
-// - Blocking:      Preempts all interaction with its modal chain
+// - Blocking:      Preempts all interaction with its modal chain excepting descendants (default mode for Dialogs)
 enum class WindowMode {
     Modeless = 0,
     Passive,