Index: lang/english.txt
===================================================================
--- lang/english.txt	(revision 5930)
+++ lang/english.txt	(working copy)
@@ -2878,4 +2878,12 @@
 STR_LARGE_AIRPORTS                                              :{BLACK}Large airports
 STR_HUB_AIRPORTS                                                :{BLACK}Hub airports
 STR_HELIPORTS                                                   :{BLACK}Helicopter airports
+
+############ Tooltip measurment
+
+STR_MEASURE_LENGTH                                              :{BLACK}Length: {NUM}
+STR_MEASURE_AREA                                                :{BLACK}Area: {NUM} x {NUM}
+STR_MEASURE_LENGTH_HEIGHTDIFF                                   :{BLACK}Length: {NUM}{}Height difference: {NUM} m
+STR_MEASURE_AREA_HEIGHTDIFF                                     :{BLACK}Area: {NUM} x {NUM}{}Height difference: {NUM} m
+
 ########
Index: misc_gui.c
===================================================================
--- misc_gui.c	(revision 5930)
+++ misc_gui.c	(working copy)
@@ -33,6 +33,8 @@
 FiosItem *_fios_list;
 int _saveload_mode;
 
+#include <stdarg.h>
+
 static bool _fios_path_changed;
 static bool _savegame_sort_dirty;
 
@@ -631,34 +633,93 @@
 static void TooltipsWndProc(Window *w, WindowEvent *e)
 {
 	switch (e->event) {
-		case WE_PAINT:
+		case WE_PAINT: {
+			uint arg;
 			GfxFillRect(0, 0, w->width - 1, w->height - 1, 0);
 			GfxFillRect(1, 1, w->width - 2, w->height - 2, 0x44);
+			for (arg = 0; arg < WP(w,tooltips_d).params; arg++) {
+				SetDParam(arg, WP(w,tooltips_d).param[arg]);
+			}
 			DrawStringMultiCenter((w->width >> 1), (w->height >> 1) - 5, WP(w,tooltips_d).string_id, 197);
 			break;
+		}
 
 		case WE_MOUSELOOP:
-			if (!_right_button_down) DeleteWindow(w);
+			if (WP(w,tooltips_d).params == 0) {
+				if (!_right_button_down) DeleteWindow(w);
+			} else {
+				if (!_left_button_down || !_shift_pressed) DeleteWindow(w);
+			}
+
 			break;
 	}
 }
 
-void GuiShowTooltips(StringID string_id)
+void GuiShowTooltips(StringID string_id, ...)
 {
+	va_list va;
 	char buffer[512];
 	Window *w;
 	int right,bottom;
-	int x,y;
+	int x = -1;
+	int y = -1;
+	uint32 param[5];
+	uint params = 0;
+	const char *string;
 
 	if (string_id == 0) return;
 
 	w = FindWindowById(WC_TOOLTIPS, 0);
 	if (w != NULL) {
-		if (WP(w,tooltips_d).string_id == string_id)
-			return;
+		if (WP(w,tooltips_d).string_id == string_id) {
+			x = w->left;
+			y = w->top;
+		}
 		DeleteWindow(w);
 	}
 
+	va_start(va, string_id);
+	for (string = GetStringPtr(string_id); *string != '\0'; string++) {
+		switch ((byte)*string) {
+			case 0x84:
+			case 0x8B:
+			case 0x8E:
+			case 0x8F:
+				param[params] = va_arg(va, int);
+				SetDParam(params, param[params]);
+				params++;
+				break;
+
+			case 0x85:
+				switch ((byte)*string++) {
+					case 3:
+					case 12:
+					case 16:
+					case 17:
+					case 18:
+					case 19:
+					case 20:
+						param[params] = va_arg(va, int);
+						SetDParam(params, param[params]);
+						params++;
+						break;
+
+					default:
+						break;
+				}
+
+			default:
+				break;
+		}
+
+		if (params == lengthof(param)) break;
+	}
+	va_end(va);
+
+	if (params != 0) //it's not a standard tooltip - it's a measurement
+		if (!_shift_pressed)
+			return;
+
 	GetString(buffer, string_id);
 
 	right = GetStringWidth(buffer) + 4;
@@ -668,8 +729,13 @@
 		bottom += ((right - 4) / 176) * 10;
 		right = 200;
 	}
+	if (string_id == STR_MEASURE_LENGTH_HEIGHTDIFF || string_id == STR_MEASURE_AREA_HEIGHTDIFF) {
+		bottom += 10; //we need an extra line for these strings.
+	}
 
 	y = _cursor.pos.y + 30;
+	if (params != 0) //it's not a standard tooltip - it's a measurement
+		y += 15;
 	if (y < 22) y = 22;
 
 	if (y > (_screen.height - 44) && (y-=52) > (_screen.height - 44))
@@ -680,10 +746,18 @@
 	if (x > (_screen.width - right)) x = _screen.width - right;
 
 	w = AllocateWindow(x, y, right, bottom, TooltipsWndProc, WC_TOOLTIPS, _tooltips_widgets);
+	
 	WP(w,tooltips_d).string_id = string_id;
-	w->flags4 &= ~WF_WHITE_BORDER_MASK;
+	if (x == -1 || y == -1) w->flags4 &= ~WF_WHITE_BORDER_MASK;
 	w->widget[0].right = right;
 	w->widget[0].bottom = bottom;
+
+	WP(w,tooltips_d).param[0] = param[0];
+	WP(w,tooltips_d).param[1] = param[1];
+	WP(w,tooltips_d).param[2] = param[2];
+	WP(w,tooltips_d).param[3] = param[3];
+	WP(w,tooltips_d).param[4] = param[4];
+	WP(w,tooltips_d).params = params;
 }
 
 
Index: network_client.c
===================================================================
--- network_client.c	(revision 5930)
+++ network_client.c	(working copy)
@@ -2,6 +2,7 @@
 
 #include "stdafx.h"
 #include "debug.h"
+#include "openttd.h"
 #include "string.h"
 #include "strings.h"
 #include "network_data.h"
Index: network_server.c
===================================================================
--- network_server.c	(revision 5930)
+++ network_server.c	(working copy)
@@ -2,6 +2,7 @@
 
 #include "stdafx.h"
 #include "debug.h"
+#include "openttd.h"
 #include "string.h"
 #include "strings.h"
 #include "network_data.h"
Index: openttd.c
===================================================================
--- openttd.c	(revision 5930)
+++ openttd.c	(working copy)
@@ -6,13 +6,13 @@
 #include "debug.h"
 #include "driver.h"
 #include "saveload.h"
-#include "strings.h"
 #include "map.h"
 #include "tile.h"
 #include "void_map.h"
 
 #define VARDEF
 #include "openttd.h"
+#include "strings.h"
 #include "bridge_map.h"
 #include "functions.h"
 #include "mixer.h"
Index: strings.c
===================================================================
--- strings.c	(revision 5930)
+++ strings.c	(working copy)
@@ -159,7 +159,7 @@
 // the indices will be reused.
 static int _bind_index;
 
-static const char *GetStringPtr(StringID string)
+const char *GetStringPtr(StringID string)
 {
 	return _langpack_offs[_langtab_start[string >> 11] + (string & 0x7FF)];
 }
Index: strings.h
===================================================================
--- strings.h	(revision 5930)
+++ strings.h	(working copy)
@@ -11,6 +11,7 @@
 	return buf;
 }
 
+const char *GetStringPtr(StringID string);
 char *GetString(char *buffr, uint16 string);
 char *GetStringWithArgs(char *buffr, uint string, const int32 *argv);
 
Index: variables.h
===================================================================
--- variables.h	(revision 5930)
+++ variables.h	(working copy)
@@ -274,7 +274,7 @@
 
 VARDEF uint32 _pressed_key; // Low 8 bits = ASCII, High 16 bits = keycode
 VARDEF bool _ctrl_pressed;  // Is Ctrl pressed?
-VARDEF bool _shift_pressed;  // Is Alt pressed?
+VARDEF bool _shift_pressed;  // Is Shift pressed?
 VARDEF byte _dirkeys;				// 1=left, 2=up, 4=right, 8=down
 
 VARDEF bool _fullscreen;
Index: viewport.c
===================================================================
--- viewport.c	(revision 5930)
+++ viewport.c	(working copy)
@@ -1925,11 +1925,24 @@
 
 void VpSetPresizeRange(uint from, uint to)
 {
+	int display_x;
+	int display_y;
 	_thd.selend.x = TileX(to) * TILE_SIZE;
 	_thd.selend.y = TileY(to) * TILE_SIZE;
 	_thd.selstart.x = TileX(from) * TILE_SIZE;
 	_thd.selstart.y = TileY(from) * TILE_SIZE;
 	_thd.next_drawstyle = HT_RECT;
+
+	//show length of tunnel/dock	
+	display_x = abs(TileX(to) - TileX(from)) + 1;
+	display_y = abs(TileY(to) - TileY(from)) + 1;
+	if (display_x > 1 ||  display_y > 1) { //show measurement only if there is any length
+		if (display_x > display_y) {
+			GuiShowTooltips(STR_MEASURE_LENGTH, display_x);
+		} else {
+			GuiShowTooltips(STR_MEASURE_LENGTH, display_y);
+		}
+	}
 }
 
 static void VpStartPreSizing(void)
@@ -1972,6 +1985,11 @@
 	return 0; // avoids compiler warnings
 }
 
+static int CalcHeightdiff(int ax, int ay, int bx, int by)
+{
+	int minimap_height_level = 50;
+	return (GetTileMaxZ(TileVirtXY(ax, ay)) * minimap_height_level / TILE_HEIGHT) - (GetTileMaxZ(TileVirtXY(bx, by)) * minimap_height_level / TILE_HEIGHT); // <-- minimap shows height in meters, let's do the same
+}
 
 // while dragging
 static void CalcRaildirsDrawstyle(TileHighlightData *thd, int x, int y, int method)
@@ -1979,6 +1997,13 @@
 	int d;
 	byte b=6;
 	uint w,h;
+	int display_x; //length in x, converted to tile format
+	int display_y; //length in y, converted to tile format
+	int distance; //length ready to be put in the toolbox
+	int heightdiff; //difference in height of two tiles:
+	int sx; //start tile coordinates
+	int sy; //end tile coordinates
+	bool diagonal = false;
 
 	int dx = thd->selstart.x - (thd->selend.x&~0xF);
 	int dy = thd->selstart.y - (thd->selend.y&~0xF);
@@ -2016,6 +2041,9 @@
 		b = HT_LINE | HT_DIR_Y;
 		x = thd->selstart.x;
 	} else { // complicated direction
+		//problem: code below treats ANY 2x1 as complicated... Hence "distance += 1;" 87 lines below
+		diagonal = true;
+		
 		d = w - h;
 		thd->selend.x = thd->selend.x & ~0xF;
 		thd->selend.y = thd->selend.y & ~0xF;
@@ -2077,6 +2105,39 @@
 	thd->selend.x = x;
 	thd->selend.y = y;
 	thd->next_drawstyle = b;
+	
+	sx = _thd.selstart.x;
+	sy = _thd.selstart.y;
+
+	heightdiff = CalcHeightdiff(x, y, sx, sy);
+
+	if (sx <= x) //player drags to the west (left)
+		display_x = x - sx + TILE_SIZE;
+	else //player drags to the east (right)
+		display_x = sx - x + 2*TILE_SIZE; // 2*TILE_SIZE will result in showing proper distance
+
+	if (sy <= y) //player drags to the south (down)
+		display_y = y - sy + TILE_SIZE;
+	else //player drags to the north (up)
+		display_y = sy - y + 2*TILE_SIZE; // 2*TILE_SIZE will result in showing proper distance
+
+	display_x /= TILE_SIZE; //convert to distance in tiles
+	display_y /= TILE_SIZE; //convert to distance in tiles
+
+	if (diagonal) {
+		distance = DistanceManhattan(TileVirtXY(sx, sy), TileVirtXY(x, y));
+		distance += 2; //add 2 to show proper measurement
+		distance /= 2; //divide, because we count one diagonal piece of rail like half of normal piece of rail
+		if (((sy - y == 1 || y - sy == 1) && x == sx) || ((sx - x == 1 || x - sx == 1) && y == sy)) { //2x1
+			distance += 1; //Unfortunatelly, all 2x1s will be 2, sorry for incovinence. But anyway, who measures that short distances?
+		}
+	} else { //player is dragging in X or Y axis (NW, NE, SW, SE)
+		distance = (myabs(sy - y) < myabs(sx - x)) ? display_x : display_y;
+	}	
+
+	heightdiff == 0
+		? GuiShowTooltips(STR_MEASURE_LENGTH, distance)
+		: GuiShowTooltips(STR_MEASURE_LENGTH_HEIGHTDIFF, distance, heightdiff);
 }
 
 // while dragging
@@ -2084,6 +2145,9 @@
 {
 	int sx;
 	int sy;
+	int display_x;
+	int display_y;
+	int heightdiff;
 
 	if (x == -1) {
 		_thd.selend.x = -1;
@@ -2106,31 +2170,65 @@
 	sx = _thd.selstart.x;
 	sy = _thd.selstart.y;
 
+	if (sx <= x) //player drags to the west (left)
+		display_x = x - sx + TILE_SIZE;
+	else //player drags to the east (right)
+		display_x = sx - x + 2*TILE_SIZE; // +2*TILE_SIZE will result in showing proper distance
+
+	if (sy <= y) //player drags to the south (down)
+		display_y = y - sy + TILE_SIZE;
+	else //player drags to the north (up)
+		display_y = sy - y + 2*TILE_SIZE; // +2*TILE_SIZE will result in showing proper distance
+
+	display_x /= TILE_SIZE; //convert to distance in tiles
+	display_y /= TILE_SIZE; //convert to distance in tiles
+	
 	switch (method) {
 		case VPM_FIX_X:
-			x = sx;
+			x = sx;	
+			heightdiff = CalcHeightdiff(x, y, sx, sy);			
+			heightdiff == 0
+				? GuiShowTooltips(STR_MEASURE_LENGTH, display_y)
+				: GuiShowTooltips(STR_MEASURE_LENGTH_HEIGHTDIFF, display_y, heightdiff);
 			break;
-
 		case VPM_FIX_Y:
 			y = sy;
-			break;
-
+			heightdiff = CalcHeightdiff(x, y, sx, sy);
+			heightdiff == 0
+				? GuiShowTooltips(STR_MEASURE_LENGTH, display_x)
+				: GuiShowTooltips(STR_MEASURE_LENGTH_HEIGHTDIFF, display_x, heightdiff);
+				break;
 		case VPM_X_OR_Y:
 			if (myabs(sy - y) < myabs(sx - x)) {
 				y = sy;
+				heightdiff = CalcHeightdiff(x, y, sx, sy);
+				heightdiff == 0
+					? GuiShowTooltips(STR_MEASURE_LENGTH, display_x)
+					: GuiShowTooltips(STR_MEASURE_LENGTH_HEIGHTDIFF, display_x, heightdiff);
 			} else {
 				x = sx;
+				heightdiff = CalcHeightdiff(x, y, sx, sy);
+				heightdiff == 0
+					? GuiShowTooltips(STR_MEASURE_LENGTH, display_y)
+					: GuiShowTooltips(STR_MEASURE_LENGTH_HEIGHTDIFF, display_y, heightdiff);
 			}
 			break;
-
 		case VPM_X_AND_Y:
+			heightdiff = CalcHeightdiff(x, y, sx, sy);
+			heightdiff == 0
+				? GuiShowTooltips(STR_MEASURE_AREA, display_x, display_y)
+				: GuiShowTooltips(STR_MEASURE_AREA_HEIGHTDIFF, display_x, display_y, heightdiff);
 			break;
-
 		// limit the selected area to a 10x10 rect.
 		case VPM_X_AND_Y_LIMITED: {
-			int limit = (_thd.sizelimit - 1) * 16;
+			int limit = (_thd.sizelimit - 1) * TILE_SIZE;
 			x = sx + clamp(x - sx, -limit, limit);
 			y = sy + clamp(y - sy, -limit, limit);
+
+			heightdiff = CalcHeightdiff(x, y, sx, sy);
+			heightdiff == 0
+				? GuiShowTooltips(STR_MEASURE_AREA, clamp(display_x, -limit, limit), clamp(display_y, -limit, limit))
+				: GuiShowTooltips(STR_MEASURE_AREA_HEIGHTDIFF, clamp(display_x, -limit, limit), clamp(display_y, -limit, limit), heightdiff);
 			break;
 		}
 	}
Index: window.c
===================================================================
--- window.c	(revision 5930)
+++ window.c	(working copy)
@@ -483,6 +483,8 @@
 
 	CallWindowEventNP(w, WE_CREATE);
 
+	if (cls == WC_TOOLTIPS) StartWindowDrag(w);
+
 	return w;
 }
 
Index: window.h
===================================================================
--- window.h	(revision 5930)
+++ window.h	(working copy)
@@ -332,6 +332,8 @@
 
 typedef struct {
 	StringID string_id;
+	uint params;
+	uint32 param[5];
 } tooltips_d;
 assert_compile(WINDOW_CUSTOM_SIZE >= sizeof(tooltips_d));
 
@@ -588,7 +590,7 @@
 void UpdateWindows(void);
 void InvalidateWidget(const Window *w, byte widget_index);
 
-void GuiShowTooltips(StringID string_id);
+void GuiShowTooltips(StringID string_id, ...);
 
 void UnclickWindowButtons(Window *w);
 void UnclickSomeWindowButtons(Window *w, uint32 mask);