From ab7ea3c8367dad3101a250bfe6873753ba1875b1 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 06 Aug 2021 00:34:48 -0400
Subject: tk: Make event callbacks optional

---
diff --git a/src/tk/button.c b/src/tk/button.c
index ffac9de..57e505a 100644
--- a/src/tk/button.c
+++ b/src/tk/button.c
@@ -51,6 +51,9 @@ _mftk_button_event(struct mftk_widget *w, SDL_Event *e,
 	switch (e->type) {
 		case SDL_MOUSEBUTTONUP:
 			if (e->button.button == SDL_BUTTON_LEFT) {
+				if (b->action == NULL) {
+					return 0;
+				}
 				return b->action(b->user_data);
 			}
 			break;
diff --git a/src/tk/check.c b/src/tk/check.c
index 6f70dd0..5c73554 100644
--- a/src/tk/check.c
+++ b/src/tk/check.c
@@ -82,6 +82,9 @@ _mftk_check_event(struct mftk_widget *w, SDL_Event *e,
 		case SDL_MOUSEBUTTONUP:
 			if (e->button.button == SDL_BUTTON_LEFT) {
 				c->state = !c->state;
+				if (c->action == NULL) {
+					return 0;
+				}
 				return c->action(c->user_data, c->state);
 			}
 			break;
diff --git a/src/tk/radio.c b/src/tk/radio.c
index 71c9486..27f7d37 100644
--- a/src/tk/radio.c
+++ b/src/tk/radio.c
@@ -53,6 +53,9 @@ _mftk_radio_state_change(void *user_data, int state)
 		mftk_check_set_state(rs->r->children[rs->r->state], SDL_FALSE);
 		/* Set and announce new state */
 		rs->r->state = rs->state;
+		if (rs->r->action == NULL) {
+			return 0;
+		}
 		return rs->r->action(rs->r->user_data, rs->r->state);
 	}
 }
--
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