Add SDL_IsTraySupported

src/tray/cocoa/SDL_tray.m

@@ -82,6 +82,16 @@ void SDL_UpdateTrays(void)
 {
 }
 
+bool SDL_IsTraySupported(void)
+{
+    if (!SDL_IsMainThread()) {
+        SDL_SetError("This function should be called on the main thread");
+        return false;
+    }
+
+    return true;
+}
+
 SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 {
     if (!SDL_IsMainThread()) {

src/tray/dummy/SDL_tray.c

@@ -29,6 +29,11 @@ void SDL_UpdateTrays(void)
 {
 }
 
+bool SDL_IsTraySupported(void)
+{
+    return false;
+}
+
 SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 {
     SDL_Unsupported();

src/tray/unix/SDL_tray.c

@@ -413,6 +413,24 @@ void SDL_UpdateTrays(void)
     }
 }
 
+bool SDL_IsTraySupported(void)
+{
+    if (!SDL_IsMainThread()) {
+        SDL_SetError("This function should be called on the main thread");
+        return false;
+    }
+
+    static bool has_trays = false;
+    static bool has_been_detected_once = false;
+
+    if (!has_been_detected_once) {
+        has_trays = init_gtk();
+        has_been_detected_once = true;
+    }
+
+    return has_trays;
+}
+
 SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 {
     if (!SDL_IsMainThread()) {

src/tray/windows/SDL_tray.c

@@ -216,6 +216,16 @@ void SDL_UpdateTrays(void)
 {
 }
 
+bool SDL_IsTraySupported(void)
+{
+    if (!SDL_IsMainThread()) {
+        SDL_SetError("This function should be called on the main thread");
+        return false;
+    }
+
+    return true;
+}
+
 SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 {
     if (!SDL_IsMainThread()) {