Add a simple MsgBox() :^)

Widgets/MsgBox.cpp

@@ -0,0 +1,59 @@
+#include "MsgBox.h"
+#include "Font.h"
+#include "AbstractScreen.h"
+#include "Window.h"
+#include "Label.h"
+#include "Button.h"
+
+void MsgBox(Window* owner, String&& text)
+{
+    Font& font = Font::defaultFont();
+    auto screenRect = AbstractScreen::the().rect();
+
+    unsigned textWidth = text.length() * font.glyphWidth() + 8;
+    unsigned textHeight = font.glyphHeight() + 8;
+    unsigned horizontalPadding = 16;
+    unsigned verticalPadding = 16;
+    unsigned buttonWidth = 60;
+    unsigned buttonHeight = 20;
+    unsigned windowWidth = textWidth + horizontalPadding * 2;
+    unsigned windowHeight = textHeight + buttonHeight + verticalPadding * 3;
+
+    Rect windowRect(
+        screenRect.center().x() - windowWidth / 2,
+        screenRect.center().y() - windowHeight / 2,
+        windowWidth,
+        windowHeight
+    );
+
+    Rect buttonRect(
+        windowWidth / 2 - buttonWidth / 2,
+        windowHeight - verticalPadding - buttonHeight,
+        buttonWidth,
+        buttonHeight
+    );
+
+    auto* window = new Window;
+    window->setTitle("MsgBox");
+    window->setRect(windowRect);
+    auto* widget = new Widget;
+    widget->setWindowRelativeRect({ 0, 0, windowWidth, windowHeight });
+    widget->setFillWithBackgroundColor(true);
+    window->setMainWidget(widget);
+    auto* label = new Label(widget);
+    label->setWindowRelativeRect({
+        horizontalPadding,
+        verticalPadding,
+        textWidth,
+        textHeight
+    });
+    label->setText(std::move(text));
+    auto* button = new Button(widget);
+    button->setCaption("OK");
+    button->setWindowRelativeRect(buttonRect);
+    button->onClick = [] (Button& button) {
+        printf("MsgBox button pressed, closing MsgBox :)\n");
+        button.window()->close();
+    };
+}
+