diff --git a/Build/Configurations/Includes/Common.cfg b/Build/Configurations/Includes/Common.cfg
index 7583ae05..981eefa4 100644
--- a/Build/Configurations/Includes/Common.cfg
+++ b/Build/Configurations/Includes/Common.cfg
@@ -15,6 +15,14 @@ start3dmode = 32000;
 // Flat used as sky
 skyflatname = "F_SKY1";
 
+// Map boundaries. Map objects can only be placed within these boundaries
+// WARNING: changing this may mess your map up, so only change it when you
+// know what you are doing
+leftboundary = -32768;
+rightboundary = 32767;
+topboundary = 32767;
+bottomboundary = -32768;
+
 
 // Maximum length of texture name length in characters (0 for unlimited)
 // WARNING: changing this may destroy your WAD file. Only change it when
diff --git a/Source/Core/Config/GameConfiguration.cs b/Source/Core/Config/GameConfiguration.cs
index e994f20f..cf2dac01 100644
--- a/Source/Core/Config/GameConfiguration.cs
+++ b/Source/Core/Config/GameConfiguration.cs
@@ -73,6 +73,10 @@ namespace CodeImp.DoomBuilder.Config
 		private string decorategames;
         private string skyflatname;
 		private int maxtexturenamelength;
+		private int leftboundary;
+		private int rightboundary;
+		private int topboundary;
+		private int bottomboundary;
 		private bool doomlightlevels;
 		
 		// Skills
@@ -159,6 +163,10 @@ namespace CodeImp.DoomBuilder.Config
 		public string DecorateGames { get { return decorategames; } }
         public string SkyFlatName { get { return skyflatname; } }
 		public int MaxTextureNamelength { get { return maxtexturenamelength; } }
+		public int LeftBoundary { get { return leftboundary; } }
+		public int RightBoundary { get { return rightboundary; } }
+		public int TopBoundary { get { return topboundary; } }
+		public int BottomBoundary { get { return bottomboundary; } }
 		public bool DoomLightLevels { get { return doomlightlevels; } }
 		
 		// Skills
@@ -267,6 +275,10 @@ namespace CodeImp.DoomBuilder.Config
 			decorategames = cfg.ReadSetting("decorategames", "");
             skyflatname = cfg.ReadSetting("skyflatname", "F_SKY1");
 			maxtexturenamelength = cfg.ReadSetting("maxtexturenamelength", 8);
+			leftboundary = cfg.ReadSetting("leftboundary", -32768);
+			rightboundary = cfg.ReadSetting("rightboundary", 32767);
+			topboundary = cfg.ReadSetting("topboundary", 32767);
+			bottomboundary = cfg.ReadSetting("bottomboundary", -32768);
 			doomlightlevels = cfg.ReadSetting("doomlightlevels", true);
 			for(int i = 0; i < Linedef.NUM_ARGS; i++) makedoorargs[i] = cfg.ReadSetting("makedoorarg" + i.ToString(CultureInfo.InvariantCulture), 0);
 			
diff --git a/Source/Core/Editing/GridSetup.cs b/Source/Core/Editing/GridSetup.cs
index 9b78f487..ce6af311 100644
--- a/Source/Core/Editing/GridSetup.cs
+++ b/Source/Core/Editing/GridSetup.cs
@@ -236,8 +236,16 @@ namespace CodeImp.DoomBuilder.Editing
 		// This snaps to the nearest grid coordinate
 		public static Vector2D SnappedToGrid(Vector2D v, float gridsize, float gridsizeinv)
 		{
-			return new Vector2D((float)Math.Round(v.x * gridsizeinv) * gridsize,
-								(float)Math.Round(v.y * gridsizeinv) * gridsize);
+			Vector2D sv = new Vector2D((float)Math.Round(v.x * gridsizeinv) * gridsize,
+			                    (float)Math.Round(v.y * gridsizeinv) * gridsize);
+
+			if (sv.x < General.Map.Config.LeftBoundary) sv.x = General.Map.Config.LeftBoundary;
+			else if (sv.x > General.Map.Config.RightBoundary) sv.x = General.Map.Config.RightBoundary;
+
+			if (sv.y > General.Map.Config.TopBoundary) sv.y = General.Map.Config.TopBoundary;
+			else if (sv.y < General.Map.Config.BottomBoundary) sv.y = General.Map.Config.BottomBoundary;
+
+			return sv;
 		}
 
 		#endregion
diff --git a/Source/Core/Rendering/Plotter.cs b/Source/Core/Rendering/Plotter.cs
index 35978325..4a7199a5 100644
--- a/Source/Core/Rendering/Plotter.cs
+++ b/Source/Core/Rendering/Plotter.cs
@@ -157,29 +157,33 @@ namespace CodeImp.DoomBuilder.Rendering
 		}
 
 		// This draws a dotted grid line horizontally
-		public void DrawGridLineH(int y, ref PixelColor c)
+		public void DrawGridLineH(int y, int x1, int x2, ref PixelColor c)
 		{
 			int numpixels = visiblewidth >> 1;
 			int offset = y & 0x01;
 			int ywidth = y * width;
+			x1 = General.Clamp(x1 >> 1, 0, numpixels - 1);
+			x2 = General.Clamp(x2 >> 1, 0, numpixels - 1);
 			
-			if((y >= 0) && (y < height))
+			if ((y >= 0) && (y < height))
 			{
 				// Draw all pixels on this line
-				for(int i = 0; i < numpixels; i++) pixels[ywidth + ((i << 1) | offset)] = c;
+				for (int i = x1; i < x2; i++) pixels[ywidth + ((i << 1) | offset)] = c;
 			}
 		}
 
 		// This draws a dotted grid line vertically
-		public void DrawGridLineV(int x, ref PixelColor c)
+		public void DrawGridLineV(int x, int y1, int y2, ref PixelColor c)
 		{
 			int numpixels = visibleheight >> 1;
 			int offset = x & 0x01;
+			y1 = General.Clamp(y1 >> 1, 0, numpixels - 1);
+			y2 = General.Clamp(y2 >> 1, 0, numpixels - 1);
 			
 			if((x >= 0) && (x < width))
 			{
 				// Draw all pixels on this line
-				for(int i = 0; i < numpixels; i++) pixels[((i << 1) | offset) * width + x] = c;
+				for (int i = y1; i < y2; i++) pixels[((i << 1) | offset) * width + x] = c;
 			}
 		}
 
diff --git a/Source/Core/Rendering/Renderer2D.cs b/Source/Core/Rendering/Renderer2D.cs
index 57e15c2e..afc06bb3 100644
--- a/Source/Core/Rendering/Renderer2D.cs
+++ b/Source/Core/Rendering/Renderer2D.cs
@@ -831,9 +831,13 @@ namespace CodeImp.DoomBuilder.Rendering
 		private void RenderGrid(float size, PixelColor c, Plotter gridplotter)
 		{
 			Vector2D ltpos, rbpos;
+			Vector2D tlb, rbb;
 			Vector2D pos = new Vector2D();
 			float sizeinv = 1f / size;
-			
+			float ystart, yend;
+			float xstart, xend;
+			float from, to;
+
 			// Only render grid when not screen-filling
 			if((size * scale) > 6f)
 			{
@@ -844,21 +848,48 @@ namespace CodeImp.DoomBuilder.Rendering
 				// Clip to nearest grid
 				ltpos = GridSetup.SnappedToGrid(ltpos, size, sizeinv);
 				rbpos = GridSetup.SnappedToGrid(rbpos, size, sizeinv);
-				
+
+				// Translate top left boundary and right bottom boundary of map
+				// to screen coords
+				tlb = new Vector2D(General.Map.Config.LeftBoundary, General.Map.Config.TopBoundary).GetTransformed(translatex, translatey, scale, -scale);
+				rbb = new Vector2D(General.Map.Config.RightBoundary, General.Map.Config.BottomBoundary).GetTransformed(translatex, translatey, scale, -scale);
+
 				// Draw all horizontal grid lines
-				for(float y = ltpos.y + size; y > rbpos.y - size; y -= size)
+				ystart = rbpos.y > General.Map.Config.BottomBoundary ? rbpos.y : General.Map.Config.BottomBoundary;
+				yend = ltpos.y < General.Map.Config.TopBoundary ? ltpos.y : General.Map.Config.TopBoundary;
+
+				for (float y = ystart; y < yend + size; y += size)
 				{
+					if (y > General.Map.Config.TopBoundary) y = General.Map.Config.TopBoundary;
+					else if (y < General.Map.Config.BottomBoundary) y = General.Map.Config.BottomBoundary;
+
+					from = tlb.x < 0 ? 0 : tlb.x;
+					to = rbb.x > windowsize.Width ? windowsize.Width : rbb.x;
+
 					pos.y = y;
 					pos = pos.GetTransformed(translatex, translatey, scale, -scale);
-					gridplotter.DrawGridLineH((int)pos.y, ref c);
+
+					// Note: I'm not using Math.Ceiling in this case, because that doesn't work right.
+					gridplotter.DrawGridLineH((int)pos.y, (int)Math.Round(from + 0.49999f), (int)Math.Round(to + 0.49999f), ref c);
 				}
-				
+
 				// Draw all vertical grid lines
-				for(float x = ltpos.x - size; x < rbpos.x + size; x += size)
+				xstart = ltpos.x > General.Map.Config.LeftBoundary ? ltpos.x : General.Map.Config.LeftBoundary;
+				xend = rbpos.x < General.Map.Config.RightBoundary ? rbpos.x : General.Map.Config.RightBoundary;
+
+				for (float x = xstart; x < xend + size; x += size)
 				{
+					if (x > General.Map.Config.RightBoundary) x = General.Map.Config.RightBoundary;
+					else if (x < General.Map.Config.LeftBoundary) x = General.Map.Config.LeftBoundary;
+
+					from = tlb.y < 0 ? 0 : tlb.y;
+					to = rbb.y > windowsize.Height ? windowsize.Height : rbb.y;
+
 					pos.x = x;
 					pos = pos.GetTransformed(translatex, translatey, scale, -scale);
-					gridplotter.DrawGridLineV((int)pos.x, ref c);
+
+					// Note: I'm not using Math.Ceiling in this case, because that doesn't work right.
+					gridplotter.DrawGridLineV((int)pos.x, (int)Math.Round(from + 0.49999f), (int)Math.Round(to + 0.49999f), ref c);
 				}
 			}
 		}
diff --git a/Source/Plugins/BuilderModes/ClassicModes/DragGeometryMode.cs b/Source/Plugins/BuilderModes/ClassicModes/DragGeometryMode.cs
index c1fe7041..9669e3d0 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/DragGeometryMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/DragGeometryMode.cs
@@ -165,10 +165,20 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		{
 			Vector2D oldpos = dragitem.Position;
 			Vector2D anchorpos = dragitemposition + offset;
-			int i = 0;
+			Vector2D tl, br;
 
 			// don't move if the offset contains invalid data
 			if (!offset.IsFinite()) return false;
+
+			// Find the outmost vertices
+			tl = br = oldpositions[0];
+			for (int i = 0; i < oldpositions.Count; i++)
+			{
+				if (oldpositions[i].x < tl.x) tl.x = (int)oldpositions[i].x;
+				if (oldpositions[i].x > br.x) br.x = (int)oldpositions[i].x;
+				if (oldpositions[i].y > tl.y) tl.y = (int)oldpositions[i].y;
+				if (oldpositions[i].y < br.y) br.y = (int)oldpositions[i].y;
+			}
 			
 			// Snap to nearest?
 			if(snapnearest)
@@ -245,9 +255,17 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				offset += dragitem.Position - anchorpos;
 			}
 
+			// Make sure the offset is inside the map boundaries
+			if (offset.x + tl.x < General.Map.Config.LeftBoundary) offset.x = General.Map.Config.LeftBoundary - tl.x;
+			if (offset.x + br.x > General.Map.Config.RightBoundary) offset.x = General.Map.Config.RightBoundary - br.x;
+			if (offset.y + tl.y > General.Map.Config.TopBoundary) offset.y = General.Map.Config.TopBoundary - tl.y;
+			if (offset.y + br.y < General.Map.Config.BottomBoundary) offset.y = General.Map.Config.BottomBoundary - br.y;
+
 			// Drag item moved?
 			if(!snapgrid || (dragitem.Position != oldpos))
 			{
+				int i = 0;
+
 				// Move selected geometry
 				foreach(Vertex v in selectedverts)
 				{
diff --git a/Source/Plugins/BuilderModes/ClassicModes/DragThingsMode.cs b/Source/Plugins/BuilderModes/ClassicModes/DragThingsMode.cs
index 1bd0c730..f664a660 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/DragThingsMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/DragThingsMode.cs
@@ -157,11 +157,21 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		{
 			Vector2D oldpos = dragitem.Position;
 			Thing nearest;
-			int i = 0;
+			Vector2D tl, br;
 
 			// don't move if the offset contains invalid data
 			if (!offset.IsFinite())	return false;
-			
+
+			// Find the outmost things
+			tl = br = oldpositions[0];
+			for (int i = 0; i < oldpositions.Count; i++)
+			{
+				if (oldpositions[i].x < tl.x) tl.x = (int)oldpositions[i].x;
+				if (oldpositions[i].x > br.x) br.x = (int)oldpositions[i].x;
+				if (oldpositions[i].y > tl.y) tl.y = (int)oldpositions[i].y;
+				if (oldpositions[i].y < br.y) br.y = (int)oldpositions[i].y;
+			}
+
 			// Snap to nearest?
 			if(snapnearest)
 			{
@@ -193,9 +203,17 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				offset += (Vector2D)dragitem.Position - (dragitemposition + offset);
 			}
 
+			// Make sure the offset is inside the map boundaries
+			if (offset.x + tl.x < General.Map.Config.LeftBoundary) offset.x = General.Map.Config.LeftBoundary - tl.x;
+			if (offset.x + br.x > General.Map.Config.RightBoundary) offset.x = General.Map.Config.RightBoundary - br.x;
+			if (offset.y + tl.y > General.Map.Config.TopBoundary) offset.y = General.Map.Config.TopBoundary - tl.y;
+			if (offset.y + br.y < General.Map.Config.BottomBoundary) offset.y = General.Map.Config.BottomBoundary - br.y;
+
 			// Drag item moved?
 			if(!snapgrid || ((Vector2D)dragitem.Position != oldpos))
 			{
+				int i = 0;
+
 				// Move selected geometry
 				foreach(Thing t in selectedthings)
 				{
diff --git a/Source/Plugins/BuilderModes/ClassicModes/DrawGeometryMode.cs b/Source/Plugins/BuilderModes/ClassicModes/DrawGeometryMode.cs
index 2eea1c80..0ba819b4 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/DrawGeometryMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/DrawGeometryMode.cs
@@ -208,6 +208,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		public static DrawnVertex GetCurrentPosition(Vector2D mousemappos, bool snaptonearest, bool snaptogrid, IRenderer2D renderer, List<DrawnVertex> points)
 		{
 			DrawnVertex p = new DrawnVertex();
+			Vector2D vm = mousemappos;
 			float vrange = BuilderPlug.Me.StitchRange / renderer.Scale;
 
 			// Snap to nearest?
@@ -289,11 +290,55 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				}
 			}
 
+			// if the mouse cursor is outside the map bondaries check if the line between the last set point and the
+			// mouse cursor intersect any of the boundary lines. If it does, set the position to this intersection
+			if (points.Count > 0 &&
+				(mousemappos.x < General.Map.Config.LeftBoundary || mousemappos.x > General.Map.Config.RightBoundary ||
+				mousemappos.y > General.Map.Config.TopBoundary || mousemappos.y < General.Map.Config.BottomBoundary))
+			{
+				Line2D dline = new Line2D(mousemappos, points[points.Count - 1].pos);
+				bool foundintersection = false;
+				float u = 0.0f;
+				List<Line2D> blines = new List<Line2D>();
+
+				// lines for left, top, right and bottom bondaries
+				blines.Add(new Line2D(General.Map.Config.LeftBoundary, General.Map.Config.BottomBoundary, General.Map.Config.LeftBoundary, General.Map.Config.TopBoundary));
+				blines.Add(new Line2D(General.Map.Config.LeftBoundary, General.Map.Config.TopBoundary, General.Map.Config.RightBoundary, General.Map.Config.TopBoundary));
+				blines.Add(new Line2D(General.Map.Config.RightBoundary, General.Map.Config.TopBoundary, General.Map.Config.RightBoundary, General.Map.Config.BottomBoundary));
+				blines.Add(new Line2D(General.Map.Config.RightBoundary, General.Map.Config.BottomBoundary, General.Map.Config.LeftBoundary, General.Map.Config.BottomBoundary));
+
+				// check for intersections with boundaries
+				for (int i = 0; i < blines.Count; i++)
+				{
+					if (!foundintersection)
+					{
+						// only check for intersection if the last set point is not on the
+						// line we are checking against
+						if (blines[i].GetSideOfLine(points[points.Count - 1].pos) != 0.0f)
+						{
+							foundintersection = blines[i].GetIntersection(dline, out u);
+						}
+					}
+				}
+
+				// if there was no intersection set the position to the last set point
+				if (!foundintersection)
+					vm = points[points.Count - 1].pos;
+				else
+					vm = dline.GetCoordinatesAt(u);
+
+			}
+
+
 			// Snap to grid?
 			if(snaptogrid)
 			{
 				// Aligned to grid
-				p.pos = General.Map.Grid.SnappedToGrid(mousemappos);
+				p.pos = General.Map.Grid.SnappedToGrid(vm);
+
+				// special handling 
+				if (p.pos.x > General.Map.Config.RightBoundary) p.pos.x = General.Map.Config.RightBoundary;
+				if (p.pos.y < General.Map.Config.BottomBoundary) p.pos.y = General.Map.Config.BottomBoundary;
 				p.stitch = snaptonearest;
 				p.stitchline = snaptonearest;
 				return p;
@@ -301,7 +346,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			else
 			{
 				// Normal position
-				p.pos = mousemappos;
+				p.pos = vm;
 				p.stitch = snaptonearest;
 				p.stitchline = snaptonearest;
 				return p;
@@ -315,14 +360,18 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		}
 		
 		// This draws a point at a specific location
-		public void DrawPointAt(DrawnVertex p)
+		public bool DrawPointAt(DrawnVertex p)
 		{
-			DrawPointAt(p.pos, p.stitch, p.stitchline);
+			return DrawPointAt(p.pos, p.stitch, p.stitchline);
 		}
 		
 		// This draws a point at a specific location
-		public void DrawPointAt(Vector2D pos, bool stitch, bool stitchline)
+		public bool DrawPointAt(Vector2D pos, bool stitch, bool stitchline)
 		{
+			if (pos.x < General.Map.Config.LeftBoundary || pos.x > General.Map.Config.RightBoundary ||
+				pos.y > General.Map.Config.TopBoundary || pos.y < General.Map.Config.BottomBoundary)
+				return false;
+
 			DrawnVertex newpoint = new DrawnVertex();
 			newpoint.pos = pos;
 			newpoint.stitch = stitch;
@@ -345,6 +394,8 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					FinishDraw();
 				}
 			}
+
+			return true;
 		}
 		
 		#endregion
@@ -498,7 +549,8 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			if(General.Interface.MouseInDisplay)
 			{
 				DrawnVertex newpoint = GetCurrentPosition();
-				DrawPointAt(newpoint);
+
+				if(!DrawPointAt(newpoint)) General.Interface.DisplayStatus(StatusType.Warning, "Failed to draw point: outside of map boundaries.");
 			}
 		}
 		
diff --git a/Source/Plugins/BuilderModes/ClassicModes/EditSelectionMode.cs b/Source/Plugins/BuilderModes/ClassicModes/EditSelectionMode.cs
index c9ad817c..ec8bb34f 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/EditSelectionMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/EditSelectionMode.cs
@@ -957,6 +957,56 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			// Anything to do?
 			if((selectedthings.Count > 0) || (selectedvertices.Count > 0))
 			{
+				Vector2D tl = new Vector2D(General.Map.Config.RightBoundary, General.Map.Config.BottomBoundary);
+				Vector2D br = new Vector2D(General.Map.Config.LeftBoundary, General.Map.Config.RightBoundary);
+
+				foreach (Vertex v in selectedvertices)
+				{
+					if (v.Position.x < tl.x) tl.x = (int)v.Position.x;
+					if (v.Position.x > br.x) br.x = (int)v.Position.x;
+					if (v.Position.y > tl.y) tl.y = (int)v.Position.y;
+					if (v.Position.y < br.y) br.y = (int)v.Position.y;
+				}
+
+				foreach (Thing t in selectedthings)
+				{
+					if (t.Position.x < tl.x) tl.x = (int)t.Position.x;
+					if (t.Position.x > br.x) br.x = (int)t.Position.x;
+					if (t.Position.y > tl.y) tl.y = (int)t.Position.y;
+					if (t.Position.y < br.y) br.y = (int)t.Position.y;
+				}
+
+				// Check if the selection is outside the map boundaries
+				if (tl.x < General.Map.Config.LeftBoundary || br.x > General.Map.Config.RightBoundary ||
+					tl.y > General.Map.Config.TopBoundary || br.y < General.Map.Config.BottomBoundary)
+				{
+					General.Interface.DisplayStatus(StatusType.Warning, "Error: selection out of map boundaries.");
+
+					// If we're in the process of switching to another mode, reset to selection
+					// to its old position
+					if (modealreadyswitching == true)
+					{
+						// Reset geometry in original position
+						int index = 0;
+						foreach (Vertex v in selectedvertices)
+							v.Move(vertexpos[index++]);
+
+						index = 0;
+						foreach (Thing t in selectedthings)
+						{
+							t.Rotate(thingangle[index]);
+							t.Move(thingpos[index++]);
+						}
+
+						// Resume normal undo/redo recording
+						General.Map.UndoRedo.IgnorePropChanges = false;
+
+						General.Map.Map.Update(true, true);
+					}
+
+					return;
+				}
+
 				Cursor.Current = Cursors.AppStarting;
 
 				if(!pasting)
diff --git a/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs b/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs
index c85f4c04..37db6237 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs
@@ -369,8 +369,11 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				bool snaptogrid = General.Interface.ShiftState ^ General.Interface.SnapToGrid;
 				bool snaptonearest = General.Interface.CtrlState ^ General.Interface.AutoMerge;
 				DrawnVertex v = DrawGeometryMode.GetCurrentPosition(mousemappos, snaptonearest, snaptogrid, renderer, new List<DrawnVertex>());
-				drawmode.DrawPointAt(v);
-				General.Editing.ChangeMode(drawmode);
+
+				if (drawmode.DrawPointAt(v))
+					General.Editing.ChangeMode(drawmode);
+				else
+					General.Interface.DisplayStatus(StatusType.Warning, "Failed to draw point: outside of map boundaries.");
 			}
 			
 			base.OnEditBegin();
diff --git a/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs b/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs
index 9169e9ba..10bef4ca 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs
@@ -591,8 +591,11 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				bool snaptogrid = General.Interface.ShiftState ^ General.Interface.SnapToGrid;
 				bool snaptonearest = General.Interface.CtrlState ^ General.Interface.AutoMerge;
 				DrawnVertex v = DrawGeometryMode.GetCurrentPosition(mousemappos, snaptonearest, snaptogrid, renderer, new List<DrawnVertex>());
-				drawmode.DrawPointAt(v);
-				General.Editing.ChangeMode(drawmode);
+				
+				if(drawmode.DrawPointAt(v))
+					General.Editing.ChangeMode(drawmode);
+				else
+					General.Interface.DisplayStatus(StatusType.Warning, "Failed to draw point: outside of map boundaries.");
 			}
 			
 			base.OnEditBegin();
diff --git a/Source/Plugins/BuilderModes/ClassicModes/ThingsMode.cs b/Source/Plugins/BuilderModes/ClassicModes/ThingsMode.cs
index 62952e6c..6e6b61e7 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/ThingsMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/ThingsMode.cs
@@ -347,10 +347,18 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					// Insert a new item and select it for dragging
 					General.Map.UndoRedo.CreateUndo("Insert thing");
 					Thing t = InsertThing(mousemappos);
-					General.Map.Map.ClearSelectedThings();
-					t.Selected = true;
-					Highlight(t);
-					General.Interface.RedrawDisplay();
+
+					if (t == null)
+					{
+						General.Map.UndoRedo.WithdrawUndo();
+					}
+					else
+					{
+						General.Map.Map.ClearSelectedThings();
+						t.Selected = true;
+						Highlight(t);
+						General.Interface.RedrawDisplay();
+					}
 				}
 			}
 
@@ -537,6 +545,12 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				// Insert new thing
 				General.Map.UndoRedo.CreateUndo("Insert thing");
 				Thing t = InsertThing(mousemappos);
+
+				if (t == null)
+				{
+					General.Map.UndoRedo.WithdrawUndo();
+					return;
+				}
 				
 				// Edit the thing?
 				if(BuilderPlug.Me.EditNewThing)
@@ -562,6 +576,13 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		// This creates a new thing
 		private Thing InsertThing(Vector2D pos)
 		{
+			if (pos.x < General.Map.Config.LeftBoundary || pos.x > General.Map.Config.RightBoundary ||
+				pos.y > General.Map.Config.TopBoundary || pos.y < General.Map.Config.BottomBoundary)
+			{
+				General.Interface.DisplayStatus(StatusType.Warning, "Failed to insert thing: outside of map boundaries.");
+				return null;
+			}
+
 			// Create things at mouse position
 			Thing t = General.Map.Map.CreateThing();
 			General.Settings.ApplyDefaultThingSettings(t);
diff --git a/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs b/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs
index 5ce63704..08eb848e 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs
@@ -322,8 +322,11 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					// Start drawing mode
 					DrawGeometryMode drawmode = new DrawGeometryMode();
 					DrawnVertex v = DrawGeometryMode.GetCurrentPosition(mousemappos, snaptonearest, snaptogrid, renderer, new List<DrawnVertex>());
-					drawmode.DrawPointAt(v);
-					General.Editing.ChangeMode(drawmode);
+
+					if (drawmode.DrawPointAt(v))
+						General.Editing.ChangeMode(drawmode);
+					else
+						General.Interface.DisplayStatus(StatusType.Warning, "Failed to draw point: outside of map boundaries.");
 				}
 			}