fix error in set_snap(): should not do a redraw (draw() ) here, causing a segfault if x11/tk structures are not ready yet. add draw() in places where this function is called if there is something to draw/

src/actions.c

@@ -300,7 +300,6 @@ void set_snap(double newsnap) /*  20161212 set new snap factor and just notify n
     }
     xctx->cadhalfdotsize = CADHALFDOTSIZE * (cs < 10. ? cs : 10.) / 10.;
     tclsetdoublevar("cadsnap", cs);
-    draw();
 }
 
 void set_grid(double newgrid)

src/callback.c

@@ -2207,6 +2207,7 @@ int rstate; /* (reduced state, without ShiftMask) */
    if(key=='g' && rstate==0)                         /* half snap factor */
    {
     set_snap(c_snap / 2.0);
+    draw();
     break;
    }
    if(key=='g' && rstate==ControlMask)              /* set snap factor 20161212 */
@@ -2220,6 +2221,7 @@ int rstate; /* (reduced state, without ShiftMask) */
    if(key=='G' && rstate == 0)                                    /* double snap factor */
    {
     set_snap(c_snap * 2.0);
+    draw();
     break;
    }
    if(key=='*' && EQUAL_MODMASK)         /* svg print , 20121108 */

src/scheduler.c

@@ -4546,6 +4546,7 @@ int xschem(ClientData clientdata, Tcl_Interp *interp, int argc, const char * arg
           else if(!strcmp(argv[2], "cadsnap")) { /* set mouse snap (default: 10) */
             if(!xctx) {Tcl_SetResult(interp, not_avail, TCL_STATIC); return TCL_ERROR;}
             set_snap( atof(argv[3]) );
+            draw();
           }
           else if(!strcmp(argv[2], "color_ps")) { /* set color psoscript (1 or 0) */
             color_ps=atoi(argv[3]);