Gtk*Backend: Disable default escape-to-close alert shortcut to fix crash

Will conditionally re-enable in scenarios where we know which button
is the benign action, but for now this is the best we can do, and just
makes sense anyway.

Author: stackotter

Sources/Gtk/Utility/CSS/CSSProvider.swift

@@ -5,7 +5,7 @@ public class CSSProvider {
     var pointer: UnsafeMutablePointer<GtkCssProvider>
     var display: OpaquePointer
 
-    init(
+    public init(
         forDisplay display: OpaquePointer = gdk_display_get_default(),
         priority: UInt32 = UInt32(GTK_STYLE_PROVIDER_PRIORITY_APPLICATION)
     ) {
@@ -24,6 +24,7 @@ public class CSSProvider {
     ///
     /// Deprecated since: 4.12
     public func loadCss(from data: String) {
+        // TODO: Connect to parsing-error signal to log parsing errors.
         gtk_css_provider_load_from_data(pointer, data, gssize(data.count))
     }
 }

Sources/Gtk3/Utility/CSS/CSSProvider.swift

@@ -34,5 +34,9 @@ public class CSSProvider {
     public func loadCss(from data: String) {
         var error: UnsafeMutablePointer<GError>? = nil
         gtk_css_provider_load_from_data(pointer, data, gssize(data.count), &error)
+        if let error {
+            let message = String(cString: error.pointee.message)
+            print("warning: Failed to load CSS: \(message)")
+        }
     }
 }

Sources/Gtk3Backend/Gtk3Backend.swift

@@ -70,6 +70,14 @@ public final class Gtk3Backend: AppBackend {
                     padding-top: 11px;
                     margin-bottom: -10px;
                 }
+
+                @binding-set DisableEscape {
+                    unbind "Escape";
+                }
+
+                messagedialog {
+                    -gtk-key-bindings: DisableEscape;
+                }
                 """
             )
             gtk_style_context_add_provider_for_screen(
@@ -822,10 +830,12 @@ public final class Gtk3Backend: AppBackend {
 
     public func createAlert() -> Alert {
         let dialog = Gtk3.MessageDialog()
+
         // The Ubuntu Gtk3 theme seems to only set the bottom corner radii.
         dialog.css.set(properties: [
             .cornerRadius(13)
         ])
+
         return dialog
     }
 
@@ -847,6 +857,14 @@ public final class Gtk3Backend: AppBackend {
         responseHandler handleResponse: @escaping (Int) -> Void
     ) {
         alert.response = { _, responseId in
+            guard responseId != Int(UInt32(bitPattern: -4)) else {
+                // Ignore escape key for now. Once we support detecting
+                // the primary and secondary actions of alerts we can wire
+                // this up to whichever action is the default cancellation
+                // action.
+                return
+            }
+
             alert.destroy()
             handleResponse(responseId)
         }

Sources/GtkBackend/GtkBackend.swift

@@ -830,7 +830,19 @@ public final class GtkBackend: AppBackend {
     }
 
     public func createAlert() -> Alert {
-        Gtk.MessageDialog()
+        let dialog = Gtk.MessageDialog()
+
+        // Register a custom shortcut controller to disable the default Escape-to-close
+        // action. In future we'll probably want to conditionally re-enable this
+        // shortcut in scenarios where we know which action button is the cancel action.
+        let controller = gtk_shortcut_controller_new()
+        let trigger = gtk_shortcut_trigger_parse_string("Escape")
+        let action = gtk_callback_action_new({ _, _, _ in return 1 }, nil, { _ in })
+        let shortcut = gtk_shortcut_new(trigger, action)
+        gtk_shortcut_controller_add_shortcut(controller, shortcut)
+        gtk_widget_add_controller(dialog.widgetPointer, controller)
+
+        return dialog
     }
 
     public func updateAlert(
@@ -851,6 +863,14 @@ public final class GtkBackend: AppBackend {
         responseHandler handleResponse: @escaping (Int) -> Void
     ) {
         alert.response = { _, responseId in
+            guard responseId != Int(UInt32(bitPattern: -4)) else {
+                // Ignore escape key for now. Once we support detecting
+                // the primary and secondary actions of alerts we can wire
+                // this up to whichever action is the default cancellation
+                // action.
+                return
+            }
+
             alert.destroy()
             handleResponse(responseId)
         }