Index: simtool.cc
===================================================================
--- simtool.cc	(revision 10484)
+++ simtool.cc	(working copy)
@@ -3945,91 +3945,109 @@
 	if(!slope_t::is_single(hang)) {
 		return "Dock must be built on single slope!";
 	}
-	else {
-		// iterate up to max(len,1) to ensure that there is at least one tile of water
-		// in front of the dock
-		for(int i=0;  i<=max(len,1);  i++  ) {
-			if(!welt->is_within_limits(k-dx*i)) {
-				// need at least a single tile to navigate ...
-				return "Zu nah am Kartenrand";
-			}
-			// search for nearby stops
-			const planquadrat_t* pl = welt->access(k-dx*i);
-			for(  uint8 j=0;  j < pl->get_boden_count();  j++  ) {
-				halthandle_t test_halt = pl->get_boden_bei(j)->get_halt();
-				if(test_halt.is_bound()) {
-					if(!player_t::check_owner( player, test_halt->get_owner())) {
-						return "Das Feld gehoert\neinem anderen Spieler\n";
+
+	koord bau_pos = k;
+	int layout = 0;
+	koord dx2;
+	switch (hang) {
+	case slope_t::south:
+	case slope_t::south * 2:
+		layout = 0;
+		dx2 = koord::west;
+		break;
+	case slope_t::east:
+	case slope_t::east * 2:
+		layout = 1;
+		dx2 = koord::north;
+		break;
+	case slope_t::north:
+	case slope_t::north * 2:
+		layout = 2;
+		dx2 = koord::west;
+		bau_pos = k - desc->get_size(layout) + koord(1, 1);
+		break;
+	case slope_t::west:
+	case slope_t::west * 2:
+		layout = 3;
+		dx2 = koord::north;
+		bau_pos = k - desc->get_size(layout) + koord(1, 1);
+		break;
+	}
+
+	const koord sz = desc->get_size( layout );
+
+	if(  k==bau_pos  &&  !welt->is_within_limits(k+sz+koord(1,1))  ) {
+		// need at least a single tile to navigate ...
+		return "Zu nah am Kartenrand";
+	}
+	if(  k!=bau_pos  &&  !welt->is_within_limits(bau_pos-koord(1,1))  ) {
+		// need at least a single tile to navigate ...
+		return "Zu nah am Kartenrand";
+	}
+
+	// now we have the layout to test all relevant tiles
+	for(  sint16 y = 0; y <sz.y;  y++  ) {
+		for(  sint16 x = 0;  x < sz.x;  x++  ) {
+			koord test_k=bau_pos+koord( x, y );
+			if(grund_t *gr=welt->lookup_kartenboden(test_k)) {
+				if( !gr->is_water() ) {
+					// only allow at the side
+					bool stating_slope = (dx2 == koord::north  &&  test_k.x==k.x)  ||  (dx2 == koord::west  &&  test_k.y==k.y);
+					if(  stating_slope  ) {
+						if( gr->get_grund_hang()!=hang ) {
+							return "Dock must be built on single slope!";
+						}
+						// start tile on slope near water
+						if(gr->hat_wege()  ||  gr->get_typ()!=grund_t::boden  ||  gr->is_halt()) {
+							return NOTICE_TILE_FULL;
+						}
 					}
-					else if(!halt.is_bound()) {
-						halt = test_halt;
+					else {
+						return NOTICE_UNSUITABLE_GROUND;
 					}
-					else if(halt != test_halt) {
-						return "Several halts found.";
+				}
+				else {
+					// all other tiles in water (allowing one-tile docks on rivers)
+					if( !gr->is_water()  &&  !(len==0  &&  i==1  &&  gr->hat_weg( water_wt )) ) {
+						return NOTICE_UNSUITABLE_GROUND;
 					}
+					if( gr->find<gebaeude_t>()  ||  gr->get_depot()  ||  gr->is_halt() ) {
+						return NOTICE_TILE_FULL;
+					}
 				}
-			}
-
-			// check whether we can build something
-			const grund_t *gr=welt->lookup_kartenboden(k-dx*i);
-			if (gr->get_hoehe() != pos.z) {
-				return NOTICE_UNSUITABLE_GROUND;
-			}
-			if (i <= len) {
+				// search for nearby stops
+				const planquadrat_t* pl = welt->access(test_k);
+				for(  uint8 j=0;  j < pl->get_boden_count();  j++  ) {
+					halthandle_t test_halt = pl->get_boden_bei(j)->get_halt();
+					if(test_halt.is_bound()) {
+						if(!player_t::check_owner( player, test_halt->get_owner())) {
+							return "Das Feld gehoert\neinem anderen Spieler\n";
+						}
+						else if(!halt.is_bound()) {
+							halt = test_halt;
+						}
+						else if(halt != test_halt) {
+							return "Several halts found.";
+						}
+					}
+				}
+				// can remove everything on it (shoudl be mostly empty anyway)
 				if (const char *msg = gr->kann_alle_obj_entfernen(player)) {
 					return msg;
 				}
 			}
-
-			if (i==0) {
-				// start tile on slope near water
-				if(gr->hat_wege()  ||  gr->get_typ()!=grund_t::boden  ||  gr->is_halt()) {
-					return NOTICE_TILE_FULL;
-				}
-			}
 			else {
-				// all other tiles in water (allowing one-tile docks on rivers)
-				if (!gr->is_water()  &&  !(len==0  &&  i==1  &&  gr->hat_weg(water_wt))) {
-					return NOTICE_UNSUITABLE_GROUND;
-				}
-				if (gr->find<gebaeude_t>()  ||  gr->get_depot()  ||  gr->is_halt()) {
-					return NOTICE_TILE_FULL;
-				}
+				dbg->error( "tool_station_dock_aux", "No ground inside the world at %s!", test_k.get_str() );
+				return NOTICE_UNSUITABLE_GROUND;
 			}
 		}
 	}
 
+	// todo: delete more than one tile
+
 	// remove everything from tile
 	gr->obj_loesche_alle(player);
 
-	koord bau_pos = k;
-	int layout = 0;
-	koord dx2;
-	switch(hang) {
-		case slope_t::south:
-		case slope_t::south*2:
-			layout = 0;
-			dx2 = koord::west;
-			break;
-		case slope_t::east:
-		case slope_t::east*2:
-			layout = 1;
-			dx2 = koord::north;
-			break;
-		case slope_t::north:
-		case slope_t::north*2:
-			layout = 2;
-			dx2 = koord::west;
-			bau_pos = last_k;
-			break;
-		case slope_t::west:
-		case slope_t::west*2:
-			layout = 3;
-			dx2 = koord::north;
-			bau_pos = last_k;
-			break;
-	}
-
 	// handle 16 layouts
 	bool change_layout = false;
 	if(desc->get_all_layouts()==16) {