diff --git a/README.md b/README.md
index df4046e8..1f28ba49 100644
--- a/README.md
+++ b/README.md
@@ -1,16 +1,16 @@
 **System requirements:**
-- 2.4 GHz CPU or faster (multi-core recommended).
-- Windows XP, Vista, 7, 8 or 10.
-- Graphics card with Pixel Shader model 2.0 support.
+- 2.4 GHz CPU or faster (multi-core recommended)
+- Windows XP, Vista, 7, 8 or 10
+- Graphics card with Pixel Shader model 2.0 support
 
 **Required software:**
-- Microsoft .Net Framework 3.5 (http://www.microsoft.com/download/en/details.aspx?id=25150).
-- DirectX 9.0 Runtime (https://www.microsoft.com/en-us/download/details.aspx?id=35&44F86079-8679-400C-BFF2-9CA5F2BCBDFC=1).
+- [Microsoft .Net Framework 3.5](http://www.microsoft.com/download/en/details.aspx?id=25150)
+- [DirectX 9.0 Runtime](https://www.microsoft.com/en-us/download/details.aspx?id=35&44F86079-8679-400C-BFF2-9CA5F2BCBDFC=1)
 
 **Links:**
 - [Official thread at ZDoom.org](http://forum.zdoom.org/viewtopic.php?f=3&t=32392) 
-- [Unofficial thread at iddqd.ru (in russian)](http://i.iddqd.ru/viewtopic.php?t=522)
+- [Unofficial thread at iddqd.ru](http://i.iddqd.ru/viewtopic.php?t=522) (in russian)
 - [Git builds at DRDTeam.org](http://devbuilds.drdteam.org/doombuilder2-gzdb/) 
 
-More detailed info can be found in the **editor documentation** (Refmanual.chm).
+More detailed info can be found in the **editor documentation** (Refmanual.chm)
 
diff --git a/Source/Core/Editing/ClassicMode.cs b/Source/Core/Editing/ClassicMode.cs
index bab61bd2..821167e3 100644
--- a/Source/Core/Editing/ClassicMode.cs
+++ b/Source/Core/Editing/ClassicMode.cs
@@ -304,7 +304,7 @@ namespace CodeImp.DoomBuilder.Editing
 											   General.Map.Graphics.RenderTarget.ClientSize.Height);
 
 			Vector2D clientscale = clientsize / renderer2d.Scale;
-			int targetsize = (int)Math.Ceiling(Math.Min(clientscale.x, clientscale.y) / 32);
+			int targetsize = (int)Math.Ceiling(Math.Min(clientscale.x, clientscale.y) / 32) * 8;
 
 			// Convert to nearest power of 2
 			targetsize--;
@@ -316,7 +316,7 @@ namespace CodeImp.DoomBuilder.Editing
 			targetsize++;
 
 			// Apply changes
-			General.Map.Grid.SetGridSize(targetsize);
+			General.Map.Grid.SetGridSize(targetsize / 8f);
 		}
 
 		// This zooms to a specific level
diff --git a/Source/Core/Editing/GridSetup.cs b/Source/Core/Editing/GridSetup.cs
index 6cb25f28..d91dfe9a 100644
--- a/Source/Core/Editing/GridSetup.cs
+++ b/Source/Core/Editing/GridSetup.cs
@@ -33,8 +33,9 @@ namespace CodeImp.DoomBuilder.Editing
 	{
 		#region ================== Constants
 
-		private const int DEFAULT_GRID_SIZE = 32;
-		private const int MINIMUM_GRID_SIZE = 1; //mxd
+		private const float DEFAULT_GRID_SIZE = 32f;
+		internal const float MINIMUM_GRID_SIZE_UDMF = 0.125f; //mxd
+		internal const float MINIMUM_GRID_SIZE = 1.0f; //mxd
 
 		public const int SOURCE_TEXTURES = 0;
 		public const int SOURCE_FLATS = 1;
@@ -45,9 +46,9 @@ namespace CodeImp.DoomBuilder.Editing
 		#region ================== Variables
 
 		// Grid
-		private int gridsize;
-		private float gridsizef;
-		private float gridsizefinv;
+		private int gridsizei;
+		private float gridsize;
+		private float gridsizeinv;
 
 		// Background
 		private string background = "";
@@ -63,8 +64,8 @@ namespace CodeImp.DoomBuilder.Editing
 
 		#region ================== Properties
 
-		public int GridSize { get { return gridsize; } }
-		public float GridSizeF { get { return gridsizef; } }
+		public int GridSizeI { get { return gridsizei; } } //mxd
+		public float GridSize { get { return gridsize; } }
 		internal string BackgroundName { get { return background; } }
 		internal int BackgroundSource { get { return backsource; } }
 		internal ImageData Background { get { return backimage; } }
@@ -147,15 +148,15 @@ namespace CodeImp.DoomBuilder.Editing
 		}
 
 		// This sets the grid size
-		internal void SetGridSize(int size)
+		internal void SetGridSize(float size)
 		{
 			//mxd. Bad things happen when size <= 0
-			size = Math.Max(size, MINIMUM_GRID_SIZE);
+			size = Math.Max(size, ((General.Map != null && General.Map.UDMF) ? MINIMUM_GRID_SIZE_UDMF : MINIMUM_GRID_SIZE));
 			
 			// Change grid
-			this.gridsize = size;
-			this.gridsizef = gridsize;
-			this.gridsizefinv = 1f / gridsizef;
+			gridsize = size;
+			gridsizei = (int)Math.Max(1, Math.Round(gridsize)); //mxd
+			gridsizeinv = 1f / gridsize;
 
 			// Update in main window
 			General.MainWindow.UpdateGrid(gridsize);
@@ -213,19 +214,19 @@ namespace CodeImp.DoomBuilder.Editing
 		// This returns the next higher coordinate
 		public float GetHigher(float offset)
 		{
-			return (float)Math.Round((offset + (gridsizef * 0.5f)) * gridsizefinv) * gridsizef;
+			return (float)Math.Round((offset + (gridsize * 0.5f)) * gridsizeinv) * gridsize;
 		}
 
 		// This returns the next lower coordinate
 		public float GetLower(float offset)
 		{
-			return (float)Math.Round((offset - (gridsizef * 0.5f)) * gridsizefinv) * gridsizef;
+			return (float)Math.Round((offset - (gridsize * 0.5f)) * gridsizeinv) * gridsize;
 		}
 		
 		// This snaps to the nearest grid coordinate
 		public Vector2D SnappedToGrid(Vector2D v)
 		{
-			return SnappedToGrid(v, gridsizef, gridsizefinv);
+			return SnappedToGrid(v, gridsize, gridsizeinv);
 		}
 
 		// This snaps to the nearest grid coordinate
@@ -267,14 +268,15 @@ namespace CodeImp.DoomBuilder.Editing
 		[BeginAction("gridinc")]
 		internal void DecreaseGrid()
 		{
-			// Not lower than 1
-			if(gridsize >= 2)
+			//mxd. Not lower than 0.125 in UDMF or 1 otherwise
+			float preminsize = (General.Map.UDMF ? MINIMUM_GRID_SIZE_UDMF * 2 : MINIMUM_GRID_SIZE * 2);
+			if(gridsize >= preminsize)
 			{
 				//mxd. Disable automatic grid resizing
 				General.MainWindow.DisableDynamicGridResize();
 				
 				// Change grid
-				SetGridSize(gridsize >> 1);
+				SetGridSize(gridsize / 2);
 				
 				// Redraw display
 				General.MainWindow.RedrawDisplay();
@@ -293,7 +295,7 @@ namespace CodeImp.DoomBuilder.Editing
 				General.MainWindow.DisableDynamicGridResize();
 				
 				// Change grid
-				SetGridSize(gridsize << 1);
+				SetGridSize(gridsize * 2);
 
 				// Redraw display
 				General.MainWindow.RedrawDisplay();
diff --git a/Source/Core/Map/Linedef.cs b/Source/Core/Map/Linedef.cs
index 99978cd3..18bbd84f 100644
--- a/Source/Core/Map/Linedef.cs
+++ b/Source/Core/Map/Linedef.cs
@@ -936,7 +936,7 @@ namespace CodeImp.DoomBuilder.Map
 			float gx = General.Map.Grid.GetHigher(minx) + gridoffset.x;
 			if(gx < maxx)
 			{
-				for(; gx < maxx; gx += General.Map.Grid.GridSizeF)
+				for(; gx < maxx; gx += General.Map.Grid.GridSize)
 				{
 					// Add intersection point at this x coordinate
 					float u = (gx - minx) / (maxx - minx);
@@ -951,7 +951,7 @@ namespace CodeImp.DoomBuilder.Map
 			float gy = General.Map.Grid.GetHigher(miny) + gridoffset.y;
 			if(gy < maxy)
 			{
-				for(; gy < maxy; gy += General.Map.Grid.GridSizeF)
+				for(; gy < maxy; gy += General.Map.Grid.GridSize)
 				{
 					// Add intersection point at this y coordinate
 					float u = (gy - miny) / (maxy - miny);
diff --git a/Source/Core/Rendering/Renderer2D.cs b/Source/Core/Rendering/Renderer2D.cs
index 60f7f2b3..d6109e31 100644
--- a/Source/Core/Rendering/Renderer2D.cs
+++ b/Source/Core/Rendering/Renderer2D.cs
@@ -108,7 +108,7 @@ namespace CodeImp.DoomBuilder.Rendering
 		private bool drawmapcenter = true; //mxd
 		private bool lastdrawmapcenter = true; //mxd
 		private float lastgridscale = -1f;
-		private int lastgridsize;
+		private float lastgridsize;
 		private float lastgridx;
 		private float lastgridy;
 		private RectangleF viewport;
@@ -357,7 +357,7 @@ namespace CodeImp.DoomBuilder.Rendering
 			if(thingsvertices != null) thingsvertices.Dispose();
 			thingsvertices = null;
 			lastgridscale = -1f;
-			lastgridsize = 0;
+			lastgridsize = 0.0f;
 		}
 		
 		// Allocates new image memory to render on
@@ -413,7 +413,7 @@ namespace CodeImp.DoomBuilder.Rendering
 			
 			// Force update of view
 			lastgridscale = -1f;
-			lastgridsize = 0;
+			lastgridsize = 0.0f;
 			lastgridx = 0.0f;
 			lastgridy = 0.0f;
 			UpdateTransformations();
diff --git a/Source/Core/Windows/GridSetupForm.Designer.cs b/Source/Core/Windows/GridSetupForm.Designer.cs
index 3a0c8c69..c31a76fd 100644
--- a/Source/Core/Windows/GridSetupForm.Designer.cs
+++ b/Source/Core/Windows/GridSetupForm.Designer.cs
@@ -68,13 +68,14 @@ namespace CodeImp.DoomBuilder.Windows
 			// 
 			// gridsize
 			// 
-			this.gridsize.AllowDecimal = false;
+			this.gridsize.AllowDecimal = true;
+			this.gridsize.AllowExpressions = false;
 			this.gridsize.AllowNegative = false;
-			this.gridsize.AllowRelative = true;
+			this.gridsize.AllowRelative = false;
 			this.gridsize.ButtonStep = 8;
 			this.gridsize.ButtonStepBig = 10F;
 			this.gridsize.ButtonStepFloat = 1F;
-			this.gridsize.ButtonStepSmall = 0.1F;
+			this.gridsize.ButtonStepSmall = 0.25F;
 			this.gridsize.ButtonStepsUseModifierKeys = false;
 			this.gridsize.ButtonStepsWrapAround = false;
 			this.gridsize.Location = new System.Drawing.Point(146, 26);
@@ -117,6 +118,7 @@ namespace CodeImp.DoomBuilder.Windows
 			// backscaley
 			// 
 			this.backscaley.AllowDecimal = false;
+			this.backscaley.AllowExpressions = false;
 			this.backscaley.AllowNegative = false;
 			this.backscaley.AllowRelative = true;
 			this.backscaley.ButtonStep = 1;
@@ -135,6 +137,7 @@ namespace CodeImp.DoomBuilder.Windows
 			// backscalex
 			// 
 			this.backscalex.AllowDecimal = false;
+			this.backscalex.AllowExpressions = false;
 			this.backscalex.AllowNegative = false;
 			this.backscalex.AllowRelative = true;
 			this.backscalex.ButtonStep = 1;
@@ -153,6 +156,7 @@ namespace CodeImp.DoomBuilder.Windows
 			// backoffsety
 			// 
 			this.backoffsety.AllowDecimal = false;
+			this.backoffsety.AllowExpressions = false;
 			this.backoffsety.AllowNegative = true;
 			this.backoffsety.AllowRelative = true;
 			this.backoffsety.ButtonStep = 1;
@@ -171,6 +175,7 @@ namespace CodeImp.DoomBuilder.Windows
 			// backoffsetx
 			// 
 			this.backoffsetx.AllowDecimal = false;
+			this.backoffsetx.AllowExpressions = false;
 			this.backoffsetx.AllowNegative = true;
 			this.backoffsetx.AllowRelative = true;
 			this.backoffsetx.ButtonStep = 1;
diff --git a/Source/Core/Windows/GridSetupForm.cs b/Source/Core/Windows/GridSetupForm.cs
index 83884291..65477cad 100644
--- a/Source/Core/Windows/GridSetupForm.cs
+++ b/Source/Core/Windows/GridSetupForm.cs
@@ -141,7 +141,7 @@ namespace CodeImp.DoomBuilder.Windows
 		private void apply_Click(object sender, EventArgs e)
 		{
 			//mxd. Apply
-			int newgridsize = gridsize.GetResult(General.Map.Grid.GridSize);
+			float newgridsize = gridsize.GetResultFloat(General.Map.Grid.GridSize);
 			if(newgridsize != General.Map.Grid.GridSize)
 			{
 				//Disable automatic grid resizing
diff --git a/Source/Core/Windows/MainForm.Designer.cs b/Source/Core/Windows/MainForm.Designer.cs
index 5fc8e34b..4a678f9b 100644
--- a/Source/Core/Windows/MainForm.Designer.cs
+++ b/Source/Core/Windows/MainForm.Designer.cs
@@ -243,6 +243,9 @@ namespace CodeImp.DoomBuilder.Windows
 			this.itemgrid8 = new System.Windows.Forms.ToolStripMenuItem();
 			this.itemgrid4 = new System.Windows.Forms.ToolStripMenuItem();
 			this.itemgrid1 = new System.Windows.Forms.ToolStripMenuItem();
+			this.itemgrid05 = new System.Windows.Forms.ToolStripMenuItem();
+			this.itemgrid025 = new System.Windows.Forms.ToolStripMenuItem();
+			this.itemgrid0125 = new System.Windows.Forms.ToolStripMenuItem();
 			this.itemgridcustom = new System.Windows.Forms.ToolStripMenuItem();
 			this.zoomlabel = new System.Windows.Forms.ToolStripStatusLabel();
 			this.buttonzoom = new System.Windows.Forms.ToolStripDropDownButton();
@@ -2228,7 +2231,7 @@ namespace CodeImp.DoomBuilder.Windows
 			this.gridlabel.AutoSize = false;
 			this.gridlabel.AutoToolTip = true;
 			this.gridlabel.Name = "gridlabel";
-			this.gridlabel.Size = new System.Drawing.Size(62, 18);
+			this.gridlabel.Size = new System.Drawing.Size(64, 18);
 			this.gridlabel.Text = "32 mp";
 			this.gridlabel.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
 			this.gridlabel.TextImageRelation = System.Windows.Forms.TextImageRelation.Overlay;
@@ -2249,6 +2252,9 @@ namespace CodeImp.DoomBuilder.Windows
             this.itemgrid8,
             this.itemgrid4,
             this.itemgrid1,
+            this.itemgrid05,
+            this.itemgrid025,
+            this.itemgrid0125,
             toolStripMenuItem4,
             this.itemgridcustom});
 			this.buttongrid.Image = global::CodeImp.DoomBuilder.Properties.Resources.Grid2_arrowup;
@@ -2339,6 +2345,30 @@ namespace CodeImp.DoomBuilder.Windows
 			this.itemgrid1.Text = "1 mp";
 			this.itemgrid1.Click += new System.EventHandler(this.itemgridsize_Click);
 			// 
+			// itemgrid05
+			// 
+			this.itemgrid05.Name = "itemgrid05";
+			this.itemgrid05.Size = new System.Drawing.Size(153, 22);
+			this.itemgrid05.Tag = "0.5";
+			this.itemgrid05.Text = "0.5 mp";
+			this.itemgrid05.Click += new System.EventHandler(this.itemgridsize_Click);
+			// 
+			// itemgrid025
+			// 
+			this.itemgrid025.Name = "itemgrid025";
+			this.itemgrid025.Size = new System.Drawing.Size(153, 22);
+			this.itemgrid025.Tag = "0.25";
+			this.itemgrid025.Text = "0.25 mp";
+			this.itemgrid025.Click += new System.EventHandler(this.itemgridsize_Click);
+			// 
+			// itemgrid0125
+			// 
+			this.itemgrid0125.Name = "itemgrid0125";
+			this.itemgrid0125.Size = new System.Drawing.Size(153, 22);
+			this.itemgrid0125.Tag = "0.125";
+			this.itemgrid0125.Text = "0.125 mp";
+			this.itemgrid0125.Click += new System.EventHandler(this.itemgridsize_Click);
+			// 
 			// itemgridcustom
 			// 
 			this.itemgridcustom.Name = "itemgridcustom";
@@ -2977,6 +3007,9 @@ namespace CodeImp.DoomBuilder.Windows
 		private System.Windows.Forms.ToolStripMenuItem itemopenconfigfolder;
 		private System.Windows.Forms.ToolStripMenuItem itemopenmapincurwad;
 		private System.Windows.Forms.ToolStripMenuItem itemgrid1;
+		private System.Windows.Forms.ToolStripMenuItem itemgrid05;
+		private System.Windows.Forms.ToolStripMenuItem itemgrid025;
+		private System.Windows.Forms.ToolStripMenuItem itemgrid0125;
 		private System.Windows.Forms.ToolStripMenuItem itemzoom400;
 		private System.Windows.Forms.Label modename;
 		private System.Windows.Forms.ToolStripMenuItem itemautoclearsidetextures;
diff --git a/Source/Core/Windows/MainForm.cs b/Source/Core/Windows/MainForm.cs
index 6c238f77..a031c8f3 100644
--- a/Source/Core/Windows/MainForm.cs
+++ b/Source/Core/Windows/MainForm.cs
@@ -746,8 +746,15 @@ namespace CodeImp.DoomBuilder.Windows
 				zoomlabel.Enabled = true;
 				buttonzoom.Enabled = true;
 				gridlabel.Enabled = true;
+				itemgrid05.Visible = General.Map.UDMF; //mxd
+				itemgrid025.Visible = General.Map.UDMF; //mxd
+				itemgrid0125.Visible = General.Map.UDMF; //mxd
 				buttongrid.Enabled = true;
 				configlabel.Text = General.Map.Config.Name;
+				
+				//mxd. Raise grid size to 1 if it was lower and the map isn't in UDMF
+				if(!General.Map.UDMF && General.Map.Grid.GridSize < GridSetup.MINIMUM_GRID_SIZE)
+					General.Map.Grid.SetGridSize(GridSetup.MINIMUM_GRID_SIZE);
 			}
 			else
 			{
@@ -933,10 +940,10 @@ namespace CodeImp.DoomBuilder.Windows
 		}
 
 		// This changes grid display
-		internal void UpdateGrid(int gridsize)
+		internal void UpdateGrid(float gridsize)
 		{
 			// Update grid label
-			gridlabel.Text = (gridsize == 0 ? "--" : gridsize.ToString("###0") + " mp");
+			gridlabel.Text = (gridsize == 0 ? "--" : gridsize + " mp");
 		}
 
 		// Set grid to a specified size
@@ -951,8 +958,8 @@ namespace CodeImp.DoomBuilder.Windows
 				ToolStripMenuItem item = sender as ToolStripMenuItem;
 				if(item != null)
 				{
-					// Get integral zoom level
-					int size = int.Parse(item.Tag.ToString(), CultureInfo.InvariantCulture);
+					//mxd. Get decimal zoom level
+					float size = float.Parse(item.Tag.ToString(), CultureInfo.InvariantCulture);
 
 					//mxd. Disable automatic grid resizing
 					DisableDynamicGridResize();
diff --git a/Source/Core/Windows/ThingEditForm.cs b/Source/Core/Windows/ThingEditForm.cs
index 834c2a97..141e8ce4 100644
--- a/Source/Core/Windows/ThingEditForm.cs
+++ b/Source/Core/Windows/ThingEditForm.cs
@@ -173,9 +173,9 @@ namespace CodeImp.DoomBuilder.Windows
 			posX.Text = ((int)ft.Position.x).ToString();
 			posY.Text = ((int)ft.Position.y).ToString();
 			posZ.Text = (useabsoluteheight ? ((int)Math.Round(ft.Position.z + floorheight)).ToString() : ((int)ft.Position.z).ToString());
-			posX.ButtonStep = General.Map.Grid.GridSize;
-			posY.ButtonStep = General.Map.Grid.GridSize;
-			posZ.ButtonStep = General.Map.Grid.GridSize;
+			posX.ButtonStep = General.Map.Grid.GridSizeI;
+			posY.ButtonStep = General.Map.Grid.GridSizeI;
+			posZ.ButtonStep = General.Map.Grid.GridSizeI;
 
 			//mxd
 			thinginfo = General.Map.Data.GetThingInfoEx(ft.Type);
diff --git a/Source/Core/Windows/ThingEditFormUDMF.cs b/Source/Core/Windows/ThingEditFormUDMF.cs
index 80e5c8ad..2d59a1e9 100644
--- a/Source/Core/Windows/ThingEditFormUDMF.cs
+++ b/Source/Core/Windows/ThingEditFormUDMF.cs
@@ -197,9 +197,9 @@ namespace CodeImp.DoomBuilder.Windows
 			posX.Text = (ft.Position.x).ToString();
 			posY.Text = (ft.Position.y).ToString();
 			posZ.Text = (useabsoluteheight ? ((float)Math.Round(ft.Position.z + floorheight, General.Map.FormatInterface.VertexDecimals)).ToString() : (ft.Position.z).ToString());
-			posX.ButtonStep = General.Map.Grid.GridSize;
-			posY.ButtonStep = General.Map.Grid.GridSize;
-			posZ.ButtonStep = General.Map.Grid.GridSize;
+			posX.ButtonStep = General.Map.Grid.GridSizeI;
+			posY.ButtonStep = General.Map.Grid.GridSizeI;
+			posZ.ButtonStep = General.Map.Grid.GridSizeI;
 
 			//mxd. User vars. Should be done before adding regular fields
 			ThingTypeInfo fti = General.Map.Data.GetThingInfoEx(ft.Type);
diff --git a/Source/Plugins/BuilderModes/ClassicModes/DrawEllipseMode.cs b/Source/Plugins/BuilderModes/ClassicModes/DrawEllipseMode.cs
index 4213930d..36bdb4ab 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/DrawEllipseMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/DrawEllipseMode.cs
@@ -282,7 +282,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		{
 			if(points.Count < 2 || currentbevelwidth == bevelwidth || bevelwidth < 0) 
 			{
-				bevelwidth = Math.Min(bevelwidth + General.Map.Grid.GridSize, panel.MaxSpikiness);
+				bevelwidth = Math.Min(bevelwidth + General.Map.Grid.GridSizeI, panel.MaxSpikiness);
 				panel.Spikiness = bevelwidth;
 				Update();
 			}
@@ -292,7 +292,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		{
 			if(bevelwidth > 0 || currentbevelwidth <= bevelwidth + 1) 
 			{
-				bevelwidth = Math.Max(bevelwidth - General.Map.Grid.GridSize, panel.MinSpikiness);
+				bevelwidth = Math.Max(bevelwidth - General.Map.Grid.GridSizeI, panel.MinSpikiness);
 				panel.Spikiness = bevelwidth;
 				Update();
 			}
diff --git a/Source/Plugins/BuilderModes/ClassicModes/DrawGridMode.cs b/Source/Plugins/BuilderModes/ClassicModes/DrawGridMode.cs
index b355ac11..59160f67 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/DrawGridMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/DrawGridMode.cs
@@ -353,18 +353,18 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					break;
 
 				case GridLockMode.HORIZONTAL:
-					slicesH = width / General.Map.Grid.GridSize;
+					slicesH = width / General.Map.Grid.GridSizeI;
 					slicesV = verticalslices;
 					break;
 
 				case GridLockMode.VERTICAL:
 					slicesH = horizontalslices;
-					slicesV = height / General.Map.Grid.GridSize;
+					slicesV = height / General.Map.Grid.GridSizeI;
 					break;
 
 				case GridLockMode.BOTH:
-					slicesH = width / General.Map.Grid.GridSize;
-					slicesV = height / General.Map.Grid.GridSize;
+					slicesH = width / General.Map.Grid.GridSizeI;
+					slicesV = height / General.Map.Grid.GridSizeI;
 					break;
 			}
 
diff --git a/Source/Plugins/BuilderModes/ClassicModes/DrawRectangleMode.cs b/Source/Plugins/BuilderModes/ClassicModes/DrawRectangleMode.cs
index 856c508a..70d7a197 100644
--- a/Source/Plugins/BuilderModes/ClassicModes/DrawRectangleMode.cs
+++ b/Source/Plugins/BuilderModes/ClassicModes/DrawRectangleMode.cs
@@ -515,7 +515,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		{
 			if(points.Count < 2 || currentbevelwidth == bevelwidth || bevelwidth < 0) 
 			{
-				bevelwidth = Math.Min(bevelwidth + General.Map.Grid.GridSize, panel.MaxBevelWidth);
+				bevelwidth = Math.Min(bevelwidth + General.Map.Grid.GridSizeI, panel.MaxBevelWidth);
 				panel.BevelWidth = bevelwidth;
 				Update();
 			}
@@ -526,7 +526,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		{
 			if(currentbevelwidth == bevelwidth || bevelwidth > 0) 
 			{
-				bevelwidth = Math.Max(bevelwidth - General.Map.Grid.GridSize, panel.MinBevelWidth);
+				bevelwidth = Math.Max(bevelwidth - General.Map.Grid.GridSizeI, panel.MinBevelWidth);
 				panel.BevelWidth = bevelwidth;
 				Update();
 			}
diff --git a/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs b/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs
index 07a1b142..2bd1f97c 100644
--- a/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs
@@ -191,9 +191,9 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				deltax = prevoffsetx - newoffsetx;
 				deltay = prevoffsety - newoffsety;
 
-				if(Math.Abs(deltax) >= General.Map.Grid.GridSize) 
+				if(Math.Abs(deltax) >= General.Map.Grid.GridSizeI) 
 				{
-					deltax = General.Map.Grid.GridSize * Math.Sign(deltax);
+					deltax = General.Map.Grid.GridSizeI * Math.Sign(deltax);
 					prevoffsetx = newoffsetx;
 				} 
 				else 
@@ -201,9 +201,9 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					deltax = 0;
 				}
 
-				if(Math.Abs(deltay) >= General.Map.Grid.GridSize) 
+				if(Math.Abs(deltay) >= General.Map.Grid.GridSizeI) 
 				{
-					deltay = General.Map.Grid.GridSize * Math.Sign(deltay);
+					deltay = General.Map.Grid.GridSizeI * Math.Sign(deltay);
 					prevoffsety = newoffsety;
 				} 
 				else 
diff --git a/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySidedef.cs b/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySidedef.cs
index d6037d18..6bf98291 100644
--- a/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySidedef.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySidedef.cs
@@ -1359,9 +1359,9 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				int dx = prevoffsetx - newoffsetx;
 				int dy = prevoffsety - newoffsety;
 
-				if(Math.Abs(dx) >= General.Map.Grid.GridSize) 
+				if(Math.Abs(dx) >= General.Map.Grid.GridSizeI) 
 				{
-					dx = General.Map.Grid.GridSize * Math.Sign(dx);
+					dx = General.Map.Grid.GridSizeI * Math.Sign(dx);
 					prevoffsetx = newoffsetx;
 				} 
 				else 
@@ -1369,9 +1369,9 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					dx = 0;
 				}
 
-				if(Math.Abs(dy) >= General.Map.Grid.GridSize) 
+				if(Math.Abs(dy) >= General.Map.Grid.GridSizeI) 
 				{
-					dy = General.Map.Grid.GridSize * Math.Sign(dy);
+					dy = General.Map.Grid.GridSizeI * Math.Sign(dy);
 					prevoffsety = newoffsety;
 				} 
 				else 
diff --git a/Source/Plugins/BuilderModes/VisualModes/BaseVisualMode.cs b/Source/Plugins/BuilderModes/VisualModes/BaseVisualMode.cs
index 86532ab5..96b8b0e2 100644
--- a/Source/Plugins/BuilderModes/VisualModes/BaseVisualMode.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/BaseVisualMode.cs
@@ -2665,10 +2665,10 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		[BeginAction("movetextureright8")]	public void MoveTextureRight8() { MoveTextureByOffset(8, 0); }
 		[BeginAction("movetextureup8")]		public void MoveTextureUp8() { MoveTextureByOffset(0, -8); }
 		[BeginAction("movetexturedown8")]	public void MoveTextureDown8() { MoveTextureByOffset(0, 8); }
-		[BeginAction("movetextureleftgs")]	public void MoveTextureLeftGrid() { MoveTextureByOffset(-General.Map.Grid.GridSize, 0); }  //mxd
-		[BeginAction("movetexturerightgs")]	public void MoveTextureRightGrid() { MoveTextureByOffset(General.Map.Grid.GridSize, 0); }  //mxd
-		[BeginAction("movetextureupgs")]	public void MoveTextureUpGrid() { MoveTextureByOffset(0, -General.Map.Grid.GridSize); } //mxd
-		[BeginAction("movetexturedowngs")]	public void MoveTextureDownGrid() { MoveTextureByOffset(0, General.Map.Grid.GridSize); } //mxd
+		[BeginAction("movetextureleftgs")]	public void MoveTextureLeftGrid() { MoveTextureByOffset(-General.Map.Grid.GridSizeI, 0); }  //mxd
+		[BeginAction("movetexturerightgs")]	public void MoveTextureRightGrid() { MoveTextureByOffset(General.Map.Grid.GridSizeI, 0); }  //mxd
+		[BeginAction("movetextureupgs")]	public void MoveTextureUpGrid() { MoveTextureByOffset(0, -General.Map.Grid.GridSizeI); } //mxd
+		[BeginAction("movetexturedowngs")]	public void MoveTextureDownGrid() { MoveTextureByOffset(0, General.Map.Grid.GridSizeI); } //mxd
 
 		//mxd
 		private void MoveTextureByOffset(int ox, int oy)