Also added imgui demo code.

compile_linux.sh

@@ -102,6 +102,7 @@ ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/render_gui/imgui_impl_glfw.cpp -o
 ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/render_gui/imgui_impl_opengl3.cpp -o sfw/render_gui/imgui_impl_opengl3.o
 ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/render_gui/imgui_tables.cpp -o sfw/render_gui/imgui_tables.o
 ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/render_gui/imgui_widgets.cpp -o sfw/render_gui/imgui_widgets.o
+ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/render_gui/imgui_demo.cpp -o sfw/render_gui/imgui_demo.o
 ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/render_gui/gui.cpp -o sfw/render_gui/gui.o
 
 ccache g++ -Wall -D_REENTRANT -g -Isfw -c sfw/game_scene.cpp -o sfw/game_scene.o
@@ -150,6 +151,7 @@ ccache g++ -Wall -D_REENTRANT -g sfw/core/aabb.o sfw/core/basis.o sfw/core/color
                         sfw/render_gui/imgui_impl_opengl3.o \
                         sfw/render_gui/imgui_tables.o \
                         sfw/render_gui/imgui_widgets.o \
+                        sfw/render_gui/imgui_demo.o \
                         sfw/render_gui/gui.o \
                         sfw/game_scene.o sfw/main.o \
                         -lX11 \

sfw/render_gui/gui.cpp

@@ -32,6 +32,11 @@ void GUI::test() {
 	static bool show_another_window = false;
 	static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
+	// 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+	if (show_demo_window) {
+		ImGui::ShowDemoWindow(&show_demo_window);
+	}
+
 	// 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
 	{
 		static float f = 0.0f;