eeshow/gui/aoi.c (aoi_set_related): AoIs can now share clicks

If A is related to B, then A can receive clicks while B is hovering,
without getting B de-hovered.

Note that in aoi_set_related(A, B), more than one A can share one B,
but an A can't have more than one B.

eeshow/gui/aoi.c

@@ -83,10 +83,26 @@ bool aoi_hover(const struct aoi *aois, int x, int y)
 }
 
 
+static bool need_dehover(const struct aoi *aois)
+{
+	const struct aoi *aoi;
+
+	if (!hovering)
+		return 0;
+	if (hovering->click)
+		return 0;
+	for (aoi = aois; aoi; aoi = aoi->next)
+		if (aoi->related == hovering && aoi->click)
+			return 0;
+	return 1;
+}
+
+
 bool aoi_click(const struct aoi *aois, int x, int y)
 {
 	const struct aoi *aoi;
 
+	if (need_dehover(aois))
 		aoi_dehover();
 
 	aoi = find_aoi(aois, x, y);
@@ -97,6 +113,12 @@ bool aoi_click(const struct aoi *aois, int x, int y)
 }
 
 
+void aoi_set_related(struct aoi *aoi, const struct aoi *related)
+{
+	assert(!aoi->related);
+	aoi->related = related;
+}
+
 void aoi_remove(struct aoi **aois, const struct aoi *aoi)
 {
 	if (hovering == aoi) {

eeshow/gui/aoi.h

@@ -24,6 +24,8 @@ struct aoi {
 	void (*click)(void *user);
 	void *user;
 
+	const struct aoi *related; /* considered equal for clicks */
+
 	struct aoi *next;
 };
 
@@ -34,6 +36,8 @@ bool aoi_hover(const struct aoi *aois, int x, int y);
 
 bool aoi_click(const struct aoi *aois, int x, int y);
 
+void aoi_set_related(struct aoi *aoi, const struct aoi *related);
+
 void aoi_remove(struct aoi **aois, const struct aoi *aoi);
 void aoi_dehover(void);