(svn r18947) -Fix [FS#1510]: after clicking move up/move down in the newgrf/ai the selected item could be out of range

src/ai/ai_gui.cpp

@@ -604,6 +604,7 @@ struct AIConfigWindow : public Window {
 				if (this->selected_slot > 1) {
 					Swap(_settings_newgame.ai_config[this->selected_slot], _settings_newgame.ai_config[this->selected_slot - 1]);
 					this->selected_slot--;
+					this->vscroll.ScrollTowards(this->selected_slot);
 					this->InvalidateData();
 				}
 				break;
@@ -612,6 +613,7 @@ struct AIConfigWindow : public Window {
 				if (this->selected_slot < _settings_newgame.difficulty.max_no_competitors) {
 					Swap(_settings_newgame.ai_config[this->selected_slot], _settings_newgame.ai_config[this->selected_slot + 1]);
 					this->selected_slot++;
+					this->vscroll.ScrollTowards(this->selected_slot);
 					this->InvalidateData();
 				}
 				break;

src/newgrf_gui.cpp

@@ -777,7 +777,8 @@ struct NewGRFWindow : public Window {
 				GRFConfig **pc, *c;
 				if (this->sel == NULL) break;
 
-				for (pc = &this->list; (c = *pc) != NULL; pc = &c->next) {
+				int pos = 0;
+				for (pc = &this->list; (c = *pc) != NULL; pc = &c->next, pos++) {
 					if (c->next == this->sel) {
 						c->next = this->sel->next;
 						this->sel->next = c;
@@ -785,6 +786,7 @@ struct NewGRFWindow : public Window {
 						break;
 					}
 				}
+				this->vscroll.ScrollTowards(pos);
 				this->preset = -1;
 				this->InvalidateData();
 				break;
@@ -794,7 +796,8 @@ struct NewGRFWindow : public Window {
 				GRFConfig **pc, *c;
 				if (this->sel == NULL) break;
 
-				for (pc = &this->list; (c = *pc) != NULL; pc = &c->next) {
+				int pos = 1; // Start at 1 as we swap the selected newgrf with the next one
+				for (pc = &this->list; (c = *pc) != NULL; pc = &c->next, pos++) {
 					if (c == this->sel) {
 						*pc = c->next;
 						c->next = c->next->next;
@@ -802,6 +805,7 @@ struct NewGRFWindow : public Window {
 						break;
 					}
 				}
+				this->vscroll.ScrollTowards(pos);
 				this->preset = -1;
 				this->InvalidateData();
 				break;