Added warning about using compupted_size wrong

gui/gui.c

@@ -143,6 +143,11 @@ typedef struct GUI_Node {
 	// True iff. it (and its children) should generate draw commands.
 	bool dirty;
 
+	// NOTE(Zelaven): Don't make decisions about visual things based on this.
+	// It will be a frame off, and with dirty-redrawing it will result in the
+	//  error persisting on the screen.
+	// All sizing and positioning should be done using semantic sizes and
+	//  offsets, and should be handled in offline layouting and positioning.
 	int computed_size[GUI_AXIS2_COUNT];
 	GUI_Rectangle rect; // NOTE(Zelaven): I have no better name for this.
 } GUI_Node;