Ancient bug: when subdividing the screen many times, it gives a crash when

the amount of subwindows reaches 128 (64 areas+headers).

Added a warning instead of crash!

source/blender/include/BIF_mywindow.h

@@ -99,6 +99,7 @@ void bwin_getsinglematrix(int winid, float mat[][4]);
 void bwin_clear_viewmat(int winid);
 
 int myswinopen(int parentid, int xmin, int xmax, int ymin, int ymax);
+int myswinopen_allowed(void);
 void myswapbuffers(void);
 
 void mygetmatrix(float mat[][4]);

source/blender/src/editscreen.c

@@ -3011,7 +3011,11 @@ static void splitarea_interactive(ScrArea *area, ScrEdge *onedge)
 	
 	if(sa->win==0) return;
 	if(sa->full) return;
-
+	if(myswinopen_allowed()==0) {
+		error("Max amount of subwindows reached");
+		return;
+	}
+	
 	dir= scredge_is_horizontal(onedge)?'v':'h';
 	
 	mywinset(G.curscreen->mainwin);

source/blender/src/mywindow.c

@@ -377,11 +377,13 @@ int myswinopen(int parentid, int xmin, int xmax, int ymin, int ymax)
 		if (!swinarray[freewinid])
 			break;
 	
+	/* this case is not handled in Blender, so will crash. use myswinopen_allowed() first to check */
 	if (freewinid==MAXWIN) {
 		printf("too many windows\n");
 
 		return 0;
-	} else {
+	} 
+	else {
 		win= MEM_callocN(sizeof(*win), "winopen");
 
 		win->id= freewinid;
@@ -403,6 +405,19 @@ int myswinopen(int parentid, int xmin, int xmax, int ymin, int ymax)
 	}
 }
 
+int myswinopen_allowed(void)
+{
+	int totfree=0;
+	int freewinid;
+	
+	for (freewinid= 4; freewinid<MAXWIN; freewinid++)
+		if (swinarray[freewinid]==NULL)
+			totfree++;
+	if(totfree<2)
+		return 0;
+	return 1;
+}
+
 void mywinclose(int winid)
 {
 	if (winid<4) {