LibGUI: Add helper for constructing new TabWidget tabs

This patch adds the following convenience helper:

    auto tab_widget = GUI::TabWidget::construct();
    auto my_widget = tab_widget->add_tab<GUI::Widget>("My tab", ...);

The above is equivalent to:

    auto tab_widget = GUI::TabWidget::construct();
    auto my_widget = GUI::Widget::construct(...);
    tab_widget->add_widget("My tab", my_widget);

1 files changed, 4 insertions, 6 deletions

diff --git a/Applications/Piano/MainWidget.cpp b/Applications/Piano/MainWidget.cpp
index c70747d4c4..d8eab8d8ad 100644
--- a/Applications/Piano/MainWidget.cpp
+++ b/Applications/Piano/MainWidget.cpp
@@ -47,15 +47,13 @@ MainWidget::MainWidget(AudioEngine& audio_engine)
     m_wave_widget->set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fixed);
     m_wave_widget->set_preferred_size(0, 100);
 
-    m_roll_widget = RollWidget::construct(audio_engine);
+    m_tab_widget = add<GUI::TabWidget>();
+    m_roll_widget = m_tab_widget->add_tab<RollWidget>("Piano Roll", audio_engine);
+
     m_roll_widget->set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fill);
     m_roll_widget->set_preferred_size(0, 300);
 
-    m_sampler_widget = SamplerWidget::construct(audio_engine);
-
-    m_tab_widget = add<GUI::TabWidget>();
-    m_tab_widget->add_widget("Piano Roll", m_roll_widget);
-    m_tab_widget->add_widget("Sampler", m_sampler_widget);
+    m_tab_widget->add_tab<SamplerWidget>("Sampler", audio_engine);
 
     m_keys_and_knobs_container = add<GUI::Widget>();
     m_keys_and_knobs_container->set_layout(make<GUI::HorizontalBoxLayout>());