Work leading up to and including Day 4.

- Initial window bits
- Preliminary Nav sidebar
- Expanders
- Koto Button to reduce code duplication
- Started work on indexer

src/koto-flipper-button.h

@@ -0,0 +1,32 @@
+/* koto-flipper-button.h
+ *
+ * Copyright 2021 Joshua Strobl
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <gtk-3.0/gtk/gtk.h>
+
+G_BEGIN_DECLS
+
+#define KOTO_TYPE_FLIPPER_BUTTON (koto_flipper_button_get_type())
+
+G_DECLARE_FINAL_TYPE (KotoFlipperButton, koto_flipper_button, KOTO, FLIPPER_BUTTON, GtkButton)
+
+KotoFlipperButton* koto_flipper_button_new(gchar *initial_icon, gchar *flipped_icon, GtkIconSize size);
+void koto_flipper_button_flip(KotoFlipperButton *self);
+void koto_flipper_button_set_icon(KotoFlipperButton *self, gchar *name);
+
+G_END_DECLS