add 'select' element (WIP)

src/graphics/ui/elements/SelectBox.cpp

@@ -0,0 +1,16 @@
+#include "SelectBox.hpp"
+
+#include "Label.hpp"
+
+using namespace gui;
+
+SelectBox::SelectBox(
+    GUI& gui,
+    std::vector<Element>&& elements,
+    Element selected,
+    int contentWidth,
+    const glm::vec4& padding
+)
+    : Button(gui, selected.text, padding, nullptr, glm::vec2(contentWidth, -1)),
+      elements(std::move(elements)) {
+}