LibGUI: Allow Buttons to set themselves as default

Several apps were implementing this behavior ad hoc. This provides
a standard API as well as a comfy visual cue for default return key
behavior.

Userland/Libraries/LibGUI/Button.cpp

@@ -10,6 +10,7 @@
 #include <LibGUI/Button.h>
 #include <LibGUI/Menu.h>
 #include <LibGUI/Painter.h>
+#include <LibGUI/Window.h>
 #include <LibGfx/Font.h>
 #include <LibGfx/Palette.h>
 #include <LibGfx/StylePainter.h>
@@ -25,6 +26,16 @@ Button::Button(String text)
     set_fixed_height(22);
     set_focus_policy(GUI::FocusPolicy::StrongFocus);
 
+    on_focus_change = [this](bool has_focus, auto) {
+        if (!is_default())
+            return;
+        if (!has_focus && is<Button>(window()->focused_widget()))
+            m_another_button_has_focus = true;
+        else
+            m_another_button_has_focus = false;
+        update();
+    };
+
     REGISTER_ENUM_PROPERTY(
         "button_style", button_style, set_button_style, Gfx::ButtonStyle,
         { Gfx::ButtonStyle::Normal, "Normal" },
@@ -46,7 +57,7 @@ void Button::paint_event(PaintEvent& event)
 
     bool paint_pressed = is_being_pressed() || (m_menu && m_menu->is_visible());
 
-    Gfx::StylePainter::paint_button(painter, rect(), palette(), m_button_style, paint_pressed, is_hovered(), is_checked(), is_enabled(), is_focused());
+    Gfx::StylePainter::paint_button(painter, rect(), palette(), m_button_style, paint_pressed, is_hovered(), is_checked(), is_enabled(), is_focused(), is_default() & !another_button_has_focus());
 
     if (text().is_empty() && !m_icon)
         return;
@@ -193,4 +204,19 @@ void Button::mousemove_event(MouseEvent& event)
     AbstractButton::mousemove_event(event);
 }
 
+bool Button::is_default() const
+{
+    if (!window())
+        return false;
+    return this == window()->default_return_key_widget();
+}
+
+void Button::set_default(bool default_button)
+{
+    deferred_invoke([this, default_button] {
+        VERIFY(window());
+        window()->set_default_return_key_widget(default_button ? this : nullptr);
+    });
+}
+
 }

Userland/Libraries/LibGUI/Button.h

@@ -48,6 +48,11 @@ public:
 
     void set_menu(RefPtr<GUI::Menu>);
 
+    bool is_default() const;
+    void set_default(bool);
+
+    bool another_button_has_focus() const { return m_another_button_has_focus; }
+
 protected:
     explicit Button(String text = {});
     virtual void mousedown_event(MouseEvent&) override;
@@ -61,6 +66,7 @@ private:
     Gfx::TextAlignment m_text_alignment { Gfx::TextAlignment::Center };
     WeakPtr<Action> m_action;
     int m_icon_spacing { 4 };
+    bool m_another_button_has_focus { false };
 };
 
 }

Userland/Libraries/LibGfx/ClassicStylePainter.cpp

@@ -93,7 +93,7 @@ void ClassicStylePainter::paint_tab_button(Painter& painter, IntRect const& rect
     }
 }
 
-static void paint_button_new(Painter& painter, IntRect const& a_rect, Palette const& palette, ButtonStyle style, bool pressed, bool checked, bool hovered, bool enabled, bool focused)
+static void paint_button_new(Painter& painter, IntRect const& a_rect, Palette const& palette, ButtonStyle style, bool pressed, bool checked, bool hovered, bool enabled, bool focused, bool default_button)
 {
     Color button_color = palette.button();
     Color highlight_color = palette.threed_highlight();
@@ -111,7 +111,7 @@ static void paint_button_new(Painter& painter, IntRect const& a_rect, Palette co
     PainterStateSaver saver(painter);
 
     auto rect = a_rect;
-    if (focused) {
+    if (focused || default_button) {
         painter.draw_rect(a_rect, palette.threed_shadow2());
         rect.shrink(2, 2);
     }
@@ -165,10 +165,10 @@ static void paint_button_new(Painter& painter, IntRect const& a_rect, Palette co
     }
 }
 
-void ClassicStylePainter::paint_button(Painter& painter, IntRect const& rect, Palette const& palette, ButtonStyle button_style, bool pressed, bool hovered, bool checked, bool enabled, bool focused)
+void ClassicStylePainter::paint_button(Painter& painter, IntRect const& rect, Palette const& palette, ButtonStyle button_style, bool pressed, bool hovered, bool checked, bool enabled, bool focused, bool default_button)
 {
     if (button_style == ButtonStyle::Normal || button_style == ButtonStyle::ThickCap)
-        return paint_button_new(painter, rect, palette, button_style, pressed, checked, hovered, enabled, focused);
+        return paint_button_new(painter, rect, palette, button_style, pressed, checked, hovered, enabled, focused, default_button);
 
     if (button_style == ButtonStyle::Coolbar && !enabled)
         return;

Userland/Libraries/LibGfx/ClassicStylePainter.h

@@ -15,7 +15,7 @@ namespace Gfx {
 
 class ClassicStylePainter : public BaseStylePainter {
 public:
-    virtual void paint_button(Painter&, IntRect const&, Palette const&, ButtonStyle, bool pressed, bool hovered = false, bool checked = false, bool enabled = true, bool focused = false) override;
+    virtual void paint_button(Painter&, IntRect const&, Palette const&, ButtonStyle, bool pressed, bool hovered = false, bool checked = false, bool enabled = true, bool focused = false, bool default_button = false) override;
     virtual void paint_tab_button(Painter&, IntRect const&, Palette const&, bool active, bool hovered, bool enabled, bool top, bool in_active_window) override;
     virtual void paint_frame(Painter&, IntRect const&, Palette const&, FrameShape, FrameShadow, int thickness, bool skip_vertical_lines = false) override;
     virtual void paint_window_frame(Painter&, IntRect const&, Palette const&) override;

Userland/Libraries/LibGfx/StylePainter.cpp

@@ -23,9 +23,9 @@ void StylePainter::paint_tab_button(Painter& painter, const IntRect& rect, const
     current().paint_tab_button(painter, rect, palette, active, hovered, enabled, top, in_active_window);
 }
 
-void StylePainter::paint_button(Painter& painter, const IntRect& rect, const Palette& palette, ButtonStyle button_style, bool pressed, bool hovered, bool checked, bool enabled, bool focused)
+void StylePainter::paint_button(Painter& painter, const IntRect& rect, const Palette& palette, ButtonStyle button_style, bool pressed, bool hovered, bool checked, bool enabled, bool focused, bool default_button)
 {
-    current().paint_button(painter, rect, palette, button_style, pressed, hovered, checked, enabled, focused);
+    current().paint_button(painter, rect, palette, button_style, pressed, hovered, checked, enabled, focused, default_button);
 }
 
 void StylePainter::paint_frame(Painter& painter, const IntRect& rect, const Palette& palette, FrameShape shape, FrameShadow shadow, int thickness, bool skip_vertical_lines)

Userland/Libraries/LibGfx/StylePainter.h

@@ -37,7 +37,7 @@ class BaseStylePainter {
 public:
     virtual ~BaseStylePainter() { }
 
-    virtual void paint_button(Painter&, IntRect const&, Palette const&, ButtonStyle, bool pressed, bool hovered = false, bool checked = false, bool enabled = true, bool focused = false) = 0;
+    virtual void paint_button(Painter&, IntRect const&, Palette const&, ButtonStyle, bool pressed, bool hovered = false, bool checked = false, bool enabled = true, bool focused = false, bool default_button = false) = 0;
     virtual void paint_tab_button(Painter&, IntRect const&, Palette const&, bool active, bool hovered, bool enabled, bool top, bool in_active_window) = 0;
     virtual void paint_frame(Painter&, IntRect const&, Palette const&, FrameShape, FrameShadow, int thickness, bool skip_vertical_lines = false) = 0;
     virtual void paint_window_frame(Painter&, IntRect const&, Palette const&) = 0;
@@ -56,7 +56,7 @@ public:
     static BaseStylePainter& current();
 
     // FIXME: These are here for API compatibility, we should probably remove them and move BaseStylePainter into here
-    static void paint_button(Painter&, IntRect const&, Palette const&, ButtonStyle, bool pressed, bool hovered = false, bool checked = false, bool enabled = true, bool focused = false);
+    static void paint_button(Painter&, IntRect const&, Palette const&, ButtonStyle, bool pressed, bool hovered = false, bool checked = false, bool enabled = true, bool focused = false, bool default_button = false);
     static void paint_tab_button(Painter&, IntRect const&, Palette const&, bool active, bool hovered, bool enabled, bool top, bool in_active_window);
     static void paint_frame(Painter&, IntRect const&, Palette const&, FrameShape, FrameShadow, int thickness, bool skip_vertical_lines = false);
     static void paint_window_frame(Painter&, IntRect const&, Palette const&);