+void
+x_set_frame_alpha (struct frame *f)
+/* --------------------------------------------------------------------------
+ change the entire-frame transparency
+ -------------------------------------------------------------------------- */
+{
+ struct ns_display_info *dpyinfo = FRAME_NS_DISPLAY_INFO (f);
+ EmacsView *view = FRAME_NS_VIEW (f);
+ double alpha = 1.0;
+ double alpha_min = 1.0;
+
+ if (dpyinfo->x_highlight_frame == f)
+ alpha = f->alpha[0];
+ else
+ alpha = f->alpha[1];
+
+ if (FLOATP (Vframe_alpha_lower_limit))
+ alpha_min = XFLOAT_DATA (Vframe_alpha_lower_limit);
+ else if (INTEGERP (Vframe_alpha_lower_limit))
+ alpha_min = (XINT (Vframe_alpha_lower_limit)) / 100.0;
+
+ if (alpha < 0.0)
+ return;
+ else if (1.0 < alpha)
+ alpha = 1.0;
+ else if (0.0 <= alpha && alpha < alpha_min && alpha_min <= 1.0)
+ alpha = alpha_min;
+
+#ifdef NS_IMPL_COCOA
+ [[view window] setAlphaValue: alpha];
+#endif
+}
+