Added: holding Control key while switching to/from Visual mode will now temporarily disable position synchronization (works only when 'Synchronize camera position between 2D and 3D modes' Preferences option is enabled).

Fixed severe lock-up after finishing dragging many vertices/linedefs/sectors in Classic modes.
Updated documentation ("Synchronizing camera position").

Help/gzdb/features/all_modes/synch_camera.html

@@ -27,6 +27,9 @@
   <p><img src="synch_cam3.jpg" alt="" width="740" height="515" /></p>
   <p>If you leave Visual mode now, the map will be centered at Visual camera's location:</p>
   <p><img src="synch_cam4.jpg" alt="" width="736" height="512" /></p>
-  <p>If you don't like this behaviour, you can disable it in the <a href="../../../w_preferences.html">Preferences window</a>.</p>
+  <p>If you don't like this behaviour, disable "<b>Synchronize camera position between 2D and 3D modes</b>" <a href="../../../w_preferences.html">Preferences</a> option.</p>
+	<h2>Additional keys:</h2>
+	<p>Holding <b>Shift</b> while switching to/from Visual mode will also synchronize selected map elements.<br />
+	Holding <b>Ctrl</b> while switching to/from Visual mode will temporarily disable camera synchronization (works only when "<b>Synchronize camera position between 2D and 3D modes</b>" <a href="../../../w_preferences.html">Preferences</a> option is enabled).</p>
 </div>
 </body>

Source/Core/Editing/ClassicMode.cs

@@ -653,7 +653,8 @@ namespace CodeImp.DoomBuilder.Editing
 			if(renderer.StartOverlay(true))
 			{
 				//mxd. Center 2d view on camera position in 3d view
-				if(General.Settings.GZSynchCameras && General.Editing.PreviousMode != null && General.Editing.PreviousMode.IsSubclassOf(typeof (VisualMode)))
+				if(General.Settings.GZSynchCameras && !General.Interface.CtrlState 
+					&& General.Editing.PreviousMode != null && General.Editing.PreviousMode.IsSubclassOf(typeof(VisualMode)))
 				{
 					Vector2D campos = new Vector2D(General.Map.VisualCamera.Position.x, General.Map.VisualCamera.Position.y);
 					renderer2d.PositionView(campos.x, campos.y);

Source/Core/Geometry/Tools.cs

@@ -2269,7 +2269,7 @@ namespace CodeImp.DoomBuilder.Geometry
 		}
 
 		//mxd. Try to create/remove/reassign outer sidedefs. Selected linedefs and verts are marked
-		public static void AdjustOuterSidedefs(HashSet<Sector> selectedsectors, ICollection<Linedef> selectedlines)
+		public static void AdjustOuterSidedefs(HashSet<Sector> selectedsectors, HashSet<Linedef> selectedlines)
 		{
 			HashSet<Sidedef> outersides = new HashSet<Sidedef>();
 			HashSet<Linedef> singlesidedlines = new HashSet<Linedef>();

Source/Core/Map/MapSet.cs

@@ -2583,7 +2583,7 @@ namespace CodeImp.DoomBuilder.Map
 		}
 
 		/// <summary>mxd. This finds the line closest to the specified position excluding given list of linedefs.</summary>
-		public Linedef NearestLinedef(Vector2D pos, ICollection<Linedef> linesToExclude) 
+		public Linedef NearestLinedef(Vector2D pos, HashSet<Linedef> linesToExclude) 
 		{
 			Linedef closest = null;
 			float distance = float.MaxValue;
@@ -2591,7 +2591,7 @@ namespace CodeImp.DoomBuilder.Map
 			// Go for all linedefs in selection
 			foreach(Linedef l in linedefs) 
 			{
-				if(linesToExclude.Contains(l))	continue;
+				if(linesToExclude.Contains(l)) continue;
 				// Calculate distance and check if closer than previous find
 				float d = l.SafeDistanceToSq(pos, true);
 				if(d < distance) 

Source/Core/VisualModes/VisualMode.cs

@@ -170,33 +170,37 @@ namespace CodeImp.DoomBuilder.VisualModes
 			//mxd. Synch camera position to cursor position or center of the screen in 2d-mode
 			if(General.Settings.GZSynchCameras) 
 			{
-				//If initial position is inside or nearby a sector - adjust camera.z accordingly
+				// Keep previous camera position if Control is held and camera was previously moved in Visual mode
-				float posz = General.Map.VisualCamera.Position.z;
+				if(!General.Interface.CtrlState || General.Map.VisualCamera.Position.GetLengthSq() == 0)
-				Sector nearestsector = General.Map.Map.GetSectorByCoordinates(initialcameraposition, blockmap);
-
-				if(nearestsector == null)
 				{
-					Linedef nearestline = MapSet.NearestLinedef(General.Map.Map.Linedefs, initialcameraposition);
+					//If initial position is inside or nearby a sector - adjust camera.z accordingly
-					if(nearestline != null) 
+					float posz = General.Map.VisualCamera.Position.z;
+					Sector nearestsector = General.Map.Map.GetSectorByCoordinates(initialcameraposition, blockmap);
+
+					if(nearestsector == null)
 					{
-						float side = nearestline.SideOfLine(initialcameraposition);
+						Linedef nearestline = MapSet.NearestLinedef(General.Map.Map.Linedefs, initialcameraposition);
-						Sidedef nearestside = (side < 0.0f ? nearestline.Front : nearestline.Back) ?? (side < 0.0f ? nearestline.Back : nearestline.Front);
+						if(nearestline != null)
-						if(nearestside != null) nearestsector = nearestside.Sector;
+						{
+							float side = nearestline.SideOfLine(initialcameraposition);
+							Sidedef nearestside = (side < 0.0f ? nearestline.Front : nearestline.Back) ?? (side < 0.0f ? nearestline.Back : nearestline.Front);
+							if(nearestside != null) nearestsector = nearestside.Sector;
+						}
 					}
+
+					if(nearestsector != null)
+					{
+						int sectorheight = nearestsector.CeilHeight - nearestsector.FloorHeight;
+						if(sectorheight < 41)
+							posz = nearestsector.FloorHeight + Math.Max(16, sectorheight / 2);
+						else if(General.Map.VisualCamera.Position.z < nearestsector.FloorHeight + 41)
+							posz = nearestsector.FloorHeight + 41; // same as in doom
+						else if(General.Map.VisualCamera.Position.z > nearestsector.CeilHeight)
+							posz = nearestsector.CeilHeight - 4;
+					}
+
+					General.Map.VisualCamera.Position = new Vector3D(initialcameraposition.x, initialcameraposition.y, posz);
 				}
-
-				if(nearestsector != null) 
-				{
-					int sectorheight = nearestsector.CeilHeight - nearestsector.FloorHeight;
-                    if (sectorheight < 41)
-                        posz = nearestsector.FloorHeight + Math.Max(16, sectorheight / 2);
-                    else if (General.Map.VisualCamera.Position.z < nearestsector.FloorHeight + 41)
-                        posz = nearestsector.FloorHeight + 41; // same as in doom
-                    else if (General.Map.VisualCamera.Position.z > nearestsector.CeilHeight)
-                        posz = nearestsector.CeilHeight - 4;
-                }
-
-				General.Map.VisualCamera.Position = new Vector3D(initialcameraposition.x, initialcameraposition.y, posz);
 			} 
 			else 
 			{

Source/Plugins/BuilderModes/ClassicModes/DragLinedefsMode.cs

@@ -119,7 +119,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					HashSet<Sector> toadjust = General.Map.Map.GetUnselectedSectorsFromLinedefs(selectedlines);
 
 					// Process outer sidedefs
-					Tools.AdjustOuterSidedefs(toadjust, selectedlines);
+					Tools.AdjustOuterSidedefs(toadjust, new HashSet<Linedef>(selectedlines));
 				}
 
 				// If only a single linedef was selected, deselect it now

Source/Plugins/BuilderModes/ClassicModes/DragSectorsMode.cs

@@ -128,7 +128,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					toadjust.UnionWith(General.Map.Map.GetUnselectedSectorsFromLinedefs(selectedlines));
 
 					// Process outer sidedefs
-					Tools.AdjustOuterSidedefs(toadjust, selectedlines);
+					Tools.AdjustOuterSidedefs(toadjust, new HashSet<Linedef>(selectedlines));
 				}
 
 				// If only a single sector was selected, deselect it now

Source/Plugins/BuilderModes/ClassicModes/DragVerticesMode.cs

@@ -103,7 +103,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				{
 					// Add sectors, which have all their linedefs selected
 					// (otherwise those would be destroyed after moving the selection)
-					ICollection<Linedef> selectedlines = General.Map.Map.LinedefsFromMarkedVertices(false, true, false);
+					HashSet<Linedef> selectedlines = new HashSet<Linedef>(General.Map.Map.LinedefsFromMarkedVertices(false, true, false));
 					HashSet<Sector> toadjust = General.Map.Map.GetUnselectedSectorsFromLinedefs(selectedlines);
 
 					// Process outer sidedefs

Source/Plugins/BuilderModes/ClassicModes/EditSelectionMode.cs

@@ -1488,7 +1488,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					// Update outer sides of the selection
 					HashSet<Sector> affectedsectors = new HashSet<Sector>(General.Map.Map.GetSelectedSectors(true));
 					affectedsectors.UnionWith(General.Map.Map.GetUnselectedSectorsFromLinedefs(selectedlines));
-					Tools.AdjustOuterSidedefs(affectedsectors, selectedlines);
+					Tools.AdjustOuterSidedefs(affectedsectors, new HashSet<Linedef>(selectedlines));
 				}
 
 				// Stitch geometry

Source/Plugins/BuilderModes/ClassicModes/ThingsMode.cs

@@ -1492,11 +1492,9 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			}
 
 			//align things
-			int thingsCount = General.Map.Map.Things.Count;
-
 			foreach(Thing t in toAlign) 
 			{
-				List<Linedef> excludedLines = new List<Linedef>();
+				HashSet<Linedef> excludedLines = new HashSet<Linedef>();
 				bool aligned;
 
 				do
@@ -1507,7 +1505,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					if(!aligned) 
 					{
 						excludedLines.Add(l);
-						if(excludedLines.Count == thingsCount) 
+						if(excludedLines.Count == General.Map.Map.Linedefs.Count) 
 						{
 							ThingTypeInfo tti = General.Map.Data.GetThingInfo(t.SRB2Type);
 							General.ErrorLogger.Add(ErrorType.Warning, "Unable to align " + tti.Title + " (index " + t.Index + ") to any linedef!");

Source/Plugins/BuilderModes/ErrorChecks/ResultSectorInvalid.cs

@@ -100,7 +100,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 
 				if(!merged)
 				{
-					List<Linedef> sectorlines = new List<Linedef>(sector.Sidedefs.Count);
+					HashSet<Linedef> sectorlines = new HashSet<Linedef>();
 					foreach(Sidedef side in sector.Sidedefs) sectorlines.Add(side.Line);
 
 					if(sectorlines.Count > 0)

Source/Plugins/BuilderModes/Resources/Actions.cfg

@@ -1579,11 +1579,12 @@ gzdbvisualmode
 {
 	title = "Visual Mode";
 	category = "modes";
-	description = "Switches to the visual editing mode. Hold Shift key to invert 'Synhcronise selection between Visual and Classic modes' setting.";
+	description = "Switches to the (G)ZDoom visual editing mode. Hold Shift key to invert 'Sync selection between Visual and Classic modes' setting.";
 	allowkeys = true;
 	allowmouse = true;
 	allowscroll = true;
 	disregardshift = true;
+	disregardcontrol = true;
 	default = 81; //Q
 }
 

Source/Plugins/BuilderModes/VisualModes/BaseVisualMode.cs

@@ -3710,11 +3710,9 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			}
 
 			//align things
-			int thingsCount = General.Map.Map.Things.Count;
-
 			foreach(Thing t in things) 
 			{
-				List<Linedef> excludedLines = new List<Linedef>();
+				HashSet<Linedef> excludedLines = new HashSet<Linedef>();
 				bool aligned;
 
 				do 
@@ -3726,7 +3724,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					{
 						excludedLines.Add(l);
 
-						if(excludedLines.Count == thingsCount) 
+						if(excludedLines.Count == General.Map.Map.Linedefs.Count) 
 						{
 							ThingTypeInfo tti = General.Map.Data.GetThingInfo(t.SRB2Type);
 							General.ErrorLogger.Add(ErrorType.Warning, "Unable to align Thing ¹" + t.Index + " (" + tti.Title + ") to any linedef in a map!");