Index: source/blender/src/editscreen.c
===================================================================
RCS file: /cvsroot/bf-blender/blender/source/blender/src/editscreen.c,v
retrieving revision 1.155
diff -u -p -u -r1.155 editscreen.c
--- source/blender/src/editscreen.c	12 Apr 2007 06:21:31 -0000	1.155
+++ source/blender/src/editscreen.c	16 Apr 2007 17:31:45 -0000
@@ -745,6 +745,35 @@ void splash(void *data, int datasize, ch
 static void moveareas(ScrEdge *edge);
 static void joinarea_interactive(ScrArea *area, ScrEdge *onedge);
 static void splitarea_interactive(ScrArea *area, ScrEdge *onedge);
+static ScrArea *test_edge_area(ScrArea *sa, ScrEdge *se);
+static ScrEdge *screen_findedge(bScreen *sc, ScrVert *v1, ScrVert *v2);
+
+static int isjoinable(ScrArea *area, ScrEdge *onedge)
+{
+	struct ScrArea *sa1 = area, *sa2;
+	struct ScrEdge *se;
+	
+	sa1 = test_edge_area(sa1, onedge);
+	if(sa1==0) return 0;
+
+	/* find directions with same edge */
+	sa2= G.curscreen->areabase.first;
+	while(sa2) {
+		if(sa2 != sa1) {
+			se= screen_findedge(G.curscreen, sa2->v1, sa2->v2);
+			if(onedge==se) return 1;
+			se= screen_findedge(G.curscreen, sa2->v2, sa2->v3);
+			if(onedge==se) return 1;
+			se= screen_findedge(G.curscreen, sa2->v3, sa2->v4);
+			if(onedge==se) return 1;
+			se= screen_findedge(G.curscreen, sa2->v4, sa2->v1);
+			if(onedge==se) return 1;
+		}
+		sa2= sa2->next;
+	}
+	
+	return 0;		
+}
 
 static void screen_edge_edit_event(ScrArea *actarea, ScrEdge *actedge, short evt, short val) 
 {
@@ -757,21 +786,34 @@ static void screen_edge_edit_event(ScrAr
 		if (evt==LEFTMOUSE) {
 			moveareas(actedge);
 		} else if (evt==MIDDLEMOUSE || evt==RIGHTMOUSE) {
-			int edgeop;
-		
+			int edgeop, joinable= 1;
+			char *str;
+			
+			str= MEM_callocN(32, "temp string");
+			strcpy(str, "Split Area|");
+			
+			if(isjoinable(actarea, actedge)) {
+				strcat(str, "Join Areas|");
+				joinable= 0;
+			}
+			
 			if (!actarea->headertype) {
-				edgeop= pupmenu("Split Area|Join Areas|Add Header");
+				strcat(str, "Add Header");
+				edgeop= pupmenu(str);
 			} else {
-				edgeop= pupmenu("Split Area|Join Areas|No Header");
+				strcat(str, "No Header");
+				edgeop= pupmenu(str);
 			}
 
 			if (edgeop==1) {
 				splitarea_interactive(actarea, actedge);
-			} else if (edgeop==2) {
+			} else if (edgeop==2+joinable) {
 				joinarea_interactive(actarea, actedge);
-			} else if (edgeop==3) {
+			} else if (edgeop==3-joinable) {
 				scrarea_change_headertype(actarea, actarea->headertype?0:HEADERDOWN);
 			}
+			
+			MEM_freeN(str);
 		}
 		else blenderqread(evt, val);	// global hotkeys
 	}