Start working on a simple Launcher app.

Let GButton have an optional icon (GraphicsBitmap) that gets rendered in the
middle of the button if present.

Also add GraphicsBitmap::load_from_file() which allows mmap'ed RGBA32 files.
I wrote a little program to take "raw" files from GIMP and swizzle them into
the correct byte order.

Launcher/.gitignore

@@ -0,0 +1,3 @@
+*.o
+*.d
+FontEditor

Launcher/Makefile

@@ -0,0 +1,34 @@
+OBJS = \
+    main.o
+
+APP = Launcher
+
+ARCH_FLAGS =
+STANDARD_FLAGS = -std=c++17 -nostdinc++ -nostdlib -nostdinc
+USERLAND_FLAGS = -ffreestanding -fno-stack-protector -fno-ident
+WARNING_FLAGS = -Wextra -Wall -Wundef -Wcast-qual -Wwrite-strings
+FLAVOR_FLAGS = -march=i386 -mregparm=3 -m32 -fno-exceptions -fno-rtti -fmerge-all-constants -fno-unroll-loops -fno-pie -fno-pic
+OPTIMIZATION_FLAGS = -Oz -fno-asynchronous-unwind-tables
+INCLUDE_FLAGS = -I.. -I. -I../LibC
+
+DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+
+CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(USERLAND_FLAGS) $(FLAVOR_FLAGS) $(ARCH_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
+CXX = clang
+LD = ld
+AR = ar
+LDFLAGS = -static --strip-debug -melf_i386 -e _start --gc-sections
+
+all: $(APP)
+
+$(APP): $(OBJS)
+	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) ../LibGUI/LibGUI.a ../LibC/LibC.a
+
+.cpp.o:
+	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
+
+-include $(OBJS:%.o=%.d)
+
+clean:
+	@echo "CLEAN"; rm -f $(APPS) $(OBJS) *.d
+

Launcher/main.cpp

@@ -0,0 +1,79 @@
+#include <SharedGraphics/GraphicsBitmap.h>
+#include <LibGUI/GWindow.h>
+#include <LibGUI/GWidget.h>
+#include <LibGUI/GButton.h>
+#include <LibGUI/GEventLoop.h>
+#include <signal.h>
+#include <unistd.h>
+
+static GWindow* make_launcher_window();
+
+void handle_sigchld(int)
+{
+    dbgprintf("Launcher(%d) Got SIGCHLD\n", getpid());
+    int pid = waitpid(-1, nullptr, 0);
+    dbgprintf("Launcher(%d) waitpid() returned %d\n", getpid(), pid);
+    ASSERT(pid > 0);
+}
+
+int main(int, char**)
+{
+    signal(SIGCHLD, handle_sigchld);
+
+    GEventLoop loop;
+
+    auto* launcher_window = make_launcher_window();
+    launcher_window->set_should_exit_app_on_close(true);
+    launcher_window->show();
+
+    return loop.exec();
+}
+
+GWindow* make_launcher_window()
+{
+    auto* window = new GWindow;
+    window->set_title("Launcher");
+    window->set_rect({ 50, 50, 300, 60 });
+
+    auto* widget = new GWidget;
+    window->set_main_widget(widget);
+    widget->set_relative_rect({ 0, 0, 300, 60 });
+
+    auto* terminal_button = new GButton(widget);
+    terminal_button->set_relative_rect({ 5, 5, 50, 50 });
+    terminal_button->set_icon(GraphicsBitmap::load_from_file("/res/icons/Terminal.rgb", { 32, 32 }));
+
+    terminal_button->on_click = [] (GButton&) {
+        pid_t child_pid = fork();
+        if (!child_pid) {
+            execve("/bin/Terminal", nullptr, nullptr);
+            ASSERT_NOT_REACHED();
+        }
+    };
+
+    auto* font_editor_button = new GButton(widget);
+    font_editor_button->set_relative_rect({ 60, 5, 50, 50 });
+    font_editor_button->set_icon(GraphicsBitmap::load_from_file("/res/icons/FontEditor.rgb", { 32, 32 }));
+
+    font_editor_button->on_click = [] (GButton&) {
+        pid_t child_pid = fork();
+        if (!child_pid) {
+            execve("/bin/FontEditor", nullptr, nullptr);
+            ASSERT_NOT_REACHED();
+        }
+    };
+
+    auto* guitest_editor_button = new GButton(widget);
+    guitest_editor_button->set_relative_rect({ 115, 5, 50, 50 });
+    guitest_editor_button->set_icon(GraphicsBitmap::load_from_file("/res/icons/generic.rgb", { 32, 32 }));
+
+    guitest_editor_button->on_click = [] (GButton&) {
+        pid_t child_pid = fork();
+        if (!child_pid) {
+            execve("/bin/guitest", nullptr, nullptr);
+            ASSERT_NOT_REACHED();
+        }
+    };
+
+    return window;
+}