diff --git a/src/object_gui.cpp b/src/object_gui.cpp
new file mode 100644
--- /dev/null
+++ b/src/object_gui.cpp
@@ -0,0 +1,336 @@
+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file object_gui.cpp The GUI for objects. */
+
+#include "stdafx.h"
+#include "command_func.h"
+#include "core/geometry_func.hpp"
+#include "newgrf.h"
+#include "newgrf_object.h"
+#include "newgrf_text.h"
+#include "sprite.h"
+#include "strings_func.h"
+#include "viewport_func.h"
+#include "widgets/dropdown_type.h"
+#include "window_gui.h"
+
+#include "table/strings.h"
+
+static ObjectClassID _selected_object_class; ///< the currently visible object class
+static int _selected_object_index;           ///< the index of the selected object in the current class or -1
+
+/** Object widgets in the object picker window. */
+enum BuildObjectWidgets {
+	BOW_CLASS_DROPDOWN, ///< The dropdown with classes.
+	BOW_OBJECT_LIST,    ///< The list with objects of a given class.
+	BOW_SCROLLBAR,      ///< The scrollbar associated with the list.
+	BOW_OBJECT_SPRITE,  ///< A preview sprite of the object.
+	BOW_OBJECT_SIZE,    ///< The size of an object.
+	BOW_INFO,           ///< Other information about the object (from the NewGRF).
+};
+
+/** The window used for building objects. */
+class BuildObjectWindow : public PickerWindowBase {
+	static const int OBJECT_MARGIN = 4; ///< The margin (in pixels) around an object.
+	int line_height;                    ///< The height of a single line.
+	int object_height;                  ///< The height of the object box.
+	int info_height;                    ///< The height of the info box.
+	Scrollbar *vscroll;                 ///< The scollbar.
+
+	/** Build a dropdown list of available object classes */
+	static DropDownList *BuildObjectClassDropDown()
+	{
+		DropDownList *list = new DropDownList();
+
+		for (uint i = 0; i < ObjectClass::GetCount(); i++) {
+			list->push_back(new DropDownListStringItem(ObjectClass::GetName((ObjectClassID)i), i, false));
+		}
+
+		return list;
+	}
+
+public:
+	BuildObjectWindow(const WindowDesc *desc, Window *w) : PickerWindowBase(w)
+	{
+		this->CreateNestedTree(desc);
+
+		this->vscroll = this->GetScrollbar(BOW_SCROLLBAR);
+		this->vscroll->SetCapacity(5);
+		this->vscroll->SetPosition(0);
+
+		this->FinishInitNested(desc, 0);
+
+		this->vscroll->SetCount(ObjectClass::GetCount(_selected_object_class));
+		this->SelectFirstAvailableObject(true);
+	}
+
+	virtual ~BuildObjectWindow()
+	{
+	}
+
+	virtual void SetStringParameters(int widget) const
+	{
+		switch (widget) {
+			case BOW_CLASS_DROPDOWN:
+				SetDParam(0, ObjectClass::GetName(_selected_object_class));
+				break;
+
+			case BOW_OBJECT_SIZE: {
+				const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, _selected_object_index);
+				int size = spec == NULL ? 0 : spec->size;
+				SetDParam(0, GB(size, 0, 4));
+				SetDParam(1, GB(size, 4, 4));
+				break;
+			}
+
+			default: break;
+		}
+	}
+
+	virtual void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize)
+	{
+		switch (widget) {
+			case BOW_CLASS_DROPDOWN: {
+				Dimension d = {0, 0};
+				for (uint i = 0; i < ObjectClass::GetCount(); i++) {
+					SetDParam(0, ObjectClass::GetName((ObjectClassID)i));
+					d = maxdim(d, GetStringBoundingBox(STR_BLACK_STRING));
+				}
+				d.width += padding.width;
+				d.height += padding.height;
+				*size = maxdim(*size, d);
+				break;
+			}
+
+			case BOW_OBJECT_LIST: {
+				for (int i = 0; i < NUM_OBJECTS; i++) {
+					const ObjectSpec *spec = ObjectSpec::Get(i);
+					if (!spec->enabled) continue;
+
+					size->width = max(size->width, GetStringBoundingBox(spec->name).width);
+				}
+
+				this->line_height = FONT_HEIGHT_NORMAL + WD_MATRIX_TOP + WD_MATRIX_BOTTOM;
+				size->height = this->vscroll->GetCapacity() * this->line_height;
+				break;
+			}
+
+			case BOW_OBJECT_SPRITE: {
+				byte height = 0;
+				for (int i = 0; i < NUM_OBJECTS; i++) {
+					height = max(ObjectSpec::Get(i)->height, height);
+				}
+				this->object_height = height * TILE_HEIGHT;
+				size->height = TILE_PIXELS + this->object_height + 2 * OBJECT_MARGIN;
+				break;
+			}
+
+			case BOW_INFO:
+				size->height = this->info_height;
+				break;
+
+			default: break;
+		}
+	}
+
+	virtual void DrawWidget(const Rect &r, int widget) const
+	{
+		switch (widget) {
+			case BOW_OBJECT_LIST: {
+				int y = r.top;
+				for (uint i = this->vscroll->GetPosition(); this->vscroll->IsVisible(i) && i < ObjectClass::GetCount(_selected_object_class); i++) {
+					const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, i);
+					if (!spec->IsAvailable()) {
+						GfxFillRect(r.left + 1, y + 1, r.right - 1, y + this->line_height - 2, 0, FILLRECT_CHECKER);
+					}
+					DrawString(r.left + WD_MATRIX_LEFT, r.right + WD_MATRIX_RIGHT, y + WD_MATRIX_TOP, spec->name, ((int)i == _selected_object_index) ? TC_WHITE : TC_BLACK);
+					y += this->line_height;
+				}
+				break;
+			}
+
+			case BOW_OBJECT_SPRITE: {
+				const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, _selected_object_index);
+				if (spec == NULL) break;
+
+				DrawPixelInfo tmp_dpi;
+				/* Set up a clipping area for the preview. */
+				if (FillDrawPixelInfo(&tmp_dpi, r.left, r.top, r.right - r.left + 1, r.bottom - r.top + 1)) {
+					DrawPixelInfo *old_dpi = _cur_dpi;
+					_cur_dpi = &tmp_dpi;
+					DrawNewObjectTileInGUI((r.right - r.left) / 2 - 1, this->object_height + OBJECT_MARGIN, spec);
+					_cur_dpi = old_dpi;
+				}
+				break;
+			}
+
+			case BOW_INFO: {
+				const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, _selected_object_index);
+				if (spec == NULL) break;
+
+				/* Get the extra message for the GUI */
+				if (HasBit(spec->callback_mask, CBM_OBJ_FUND_MORE_TEXT)) {
+					uint16 callback_res = GetObjectCallback(CBID_OBJECT_FUND_MORE_TEXT, 0, 0, spec, NULL, INVALID_TILE);
+					if (callback_res != CALLBACK_FAILED) {
+						StringID message = GetGRFStringID(spec->grf_prop.grffile->grfid, 0xD000 + callback_res);
+						if (message != STR_NULL && message != STR_UNDEFINED) {
+							PrepareTextRefStackUsage(6);
+							/* Use all the available space left from where we stand up to the
+							 * end of the window. We ALSO enlarge the window if needed, so we
+							 * can 'go' wild with the bottom of the window. */
+							int y = DrawStringMultiLine(r.left, r.right, r.top, UINT16_MAX, message);
+							StopTextRefStackUsage();
+							if (y > this->info_height) {
+								BuildObjectWindow *bow = const_cast<BuildObjectWindow *>(this);
+								bow->info_height = y + 2;
+								bow->ReInit();
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+
+	virtual void OnPaint()
+	{
+		this->DrawWidgets();
+	}
+
+	void SelectOtherObject(int object_index)
+	{
+		_selected_object_index = object_index;
+
+		this->UpdateSelectSize();
+		this->SetDirty();
+	}
+
+	void UpdateSelectSize()
+	{
+		if (_selected_object_index == -1) {
+			SetTileSelectSize(1, 1);
+		} else {
+			const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, _selected_object_index);
+			int w = GB(spec->size, 0, 4);
+			int h = GB(spec->size, 4, 4);
+			SetTileSelectSize(w, h);
+		}
+	}
+
+	virtual void OnClick(Point pt, int widget, int click_count)
+	{
+		switch (widget) {
+			case BOW_CLASS_DROPDOWN:
+				ShowDropDownList(this, BuildObjectClassDropDown(), _selected_object_class, BOW_CLASS_DROPDOWN);
+				break;
+
+			case BOW_OBJECT_LIST: {
+				int num_clicked = this->vscroll->GetPosition() + (pt.y - this->nested_array[widget]->pos_y) / this->line_height;
+				if (num_clicked >= this->vscroll->GetCount()) break;
+				const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, num_clicked);
+				if (spec->IsAvailable()) this->SelectOtherObject(num_clicked);
+				break;
+			}
+		}
+	}
+
+	/**
+	 * Select the first available object.
+	 * @param change_class If true, change the class if no object in the current
+	 *   class is available.
+	 */
+	void SelectFirstAvailableObject(bool change_class)
+	{
+		/* First try to select an object in the selected class. */
+		for (uint i = 0; i < ObjectClass::GetCount(_selected_object_class); i++) {
+			const ObjectSpec *spec = ObjectClass::Get(_selected_object_class, i);
+			if (spec->IsAvailable()) {
+				this->SelectOtherObject(0);
+				return;
+			}
+		}
+		if (change_class) {
+			/* If that fails, select the first available object
+			 * from a random class. */
+			for (ObjectClassID j = OBJECT_CLASS_BEGIN; j < OBJECT_CLASS_MAX; j++) {
+				for (uint i = 0; i < ObjectClass::GetCount(j); i++) {
+					const ObjectSpec *spec = ObjectClass::Get(j, i);
+					if (spec->IsAvailable()) {
+						_selected_object_class = j;
+						this->SelectOtherObject(i);
+						return;
+					}
+				}
+			}
+		}
+		/* If all objects are unavailable, select nothing. */
+		this->SelectOtherObject(-1);
+	}
+
+	virtual void OnDropdownSelect(int widget, int index)
+	{
+		assert(widget == BOW_CLASS_DROPDOWN);
+		_selected_object_class = (ObjectClassID)index;
+		this->vscroll->SetCount(ObjectClass::GetCount(_selected_object_class));
+		this->SelectFirstAvailableObject(false);
+	}
+};
+
+static const NWidgetPart _nested_build_object_widgets[] = {
+	NWidget(NWID_HORIZONTAL),
+		NWidget(WWT_CLOSEBOX, COLOUR_DARK_GREEN),
+		NWidget(WWT_CAPTION, COLOUR_DARK_GREEN), SetDataTip(STR_OBJECT_BUILD_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
+	EndContainer(),
+	NWidget(WWT_PANEL, COLOUR_DARK_GREEN), SetFill(1, 0),
+		NWidget(WWT_LABEL, COLOUR_DARK_GREEN), SetPadding(2, 5, 2, 5), SetDataTip(STR_OBJECT_BUILD_CLASS_LABEL, STR_NULL), SetFill(1, 0),
+		NWidget(WWT_DROPDOWN, COLOUR_GREY, BOW_CLASS_DROPDOWN), SetPadding(0, 5, 2, 5), SetFill(1, 0), SetDataTip(STR_BLACK_STRING, STR_OBJECT_BUILD_TOOLTIP),
+		NWidget(NWID_HORIZONTAL), SetPadding(0, 5, 2, 5),
+			NWidget(WWT_MATRIX, COLOUR_GREY, BOW_OBJECT_LIST), SetFill(1, 0), SetDataTip(0x501, STR_OBJECT_BUILD_TOOLTIP), SetScrollbar(BOW_SCROLLBAR),
+			NWidget(NWID_VSCROLLBAR, COLOUR_GREY, BOW_SCROLLBAR),
+		EndContainer(),
+		NWidget(NWID_HORIZONTAL), SetPadding(0, 5, 0, 5),
+			NWidget(WWT_PANEL, COLOUR_GREY, BOW_OBJECT_SPRITE), SetMinimalSize(130, 0), SetFill(1, 0), SetDataTip(0x0, STR_STATION_BUILD_RAILROAD_ORIENTATION_TOOLTIP), EndContainer(),
+		EndContainer(),
+		NWidget(WWT_TEXT, COLOUR_DARK_GREEN, BOW_OBJECT_SIZE), SetDataTip(STR_OBJECT_BUILD_SIZE, STR_NULL), SetPadding(2, 5, 2, 5),
+		NWidget(WWT_PANEL, COLOUR_DARK_GREEN, BOW_INFO), SetPadding(2, 5, 0, 5),
+	EndContainer(),
+};
+
+static const WindowDesc _build_object_desc(
+	WDP_AUTO, 0, 0,
+	WC_BUILD_OBJECT, WC_BUILD_TOOLBAR,
+	WDF_CONSTRUCTION,
+	_nested_build_object_widgets, lengthof(_nested_build_object_widgets)
+);
+
+/**
+ * Show our object picker.
+ * @param w The toolbar window we're associated with.
+ */
+void ShowBuildObjectPicker(Window *w)
+{
+	new BuildObjectWindow(&_build_object_desc, w);
+}
+
+/** Reset all data of the object GUI. */
+void InitializeObjectGui()
+{
+	_selected_object_class = (ObjectClassID)0;
+}
+
+/**
+ * PlaceProc function, called when someone pressed the button if the
+ *  object-tool is selected
+ * @param tile on which to place the object
+ */
+void PlaceProc_Object(TileIndex tile)
+{
+	DoCommandP(tile, ObjectClass::Get(_selected_object_class, _selected_object_index)->Index(), 0, CMD_BUILD_OBJECT | CMD_MSG(STR_ERROR_CAN_T_BUILD_OBJECT), CcTerraform);
+}