Fixed: selected items info was not updated when deleting a map element.

Changed, Sound Environments mode: previously selected sound environment is now automatically selected when inserting a new sound environment item. Also it's now impossible to accept the form without selecting a sound environment.
Changed, Sound Propagation mode: single-sided lines with sound zone boundary flag are now highlightable and clickable.

Source/Plugins/BuilderModes/ClassicModes/LinedefsMode.cs

@@ -983,6 +983,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			OnMouseMove(e);
 
 			// Redraw screen
+			UpdateSelectionInfo(); //mxd
 			General.Map.Renderer2D.UpdateExtraFloorFlag(); //mxd
 			General.Interface.RedrawDisplay();
 		}
@@ -1052,6 +1053,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				OnMouseMove(e);
 				
 				// Redraw screen
+				UpdateSelectionInfo(); //mxd
 				General.Map.Renderer2D.UpdateExtraFloorFlag(); //mxd
 				General.Interface.RedrawDisplay();
 			}

Source/Plugins/BuilderModes/ClassicModes/SectorsMode.cs

@@ -1618,6 +1618,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				UpdateSelectedLabels();
 				
 				// Redraw screen
+				UpdateSelectionInfo(); //mxd
 				General.Map.Renderer2D.UpdateExtraFloorFlag(); //mxd
 				General.Interface.RedrawDisplay();
 			}

Source/Plugins/BuilderModes/ClassicModes/ThingsMode.cs

@@ -888,6 +888,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 				OnMouseMove(e);
 
 				// Redraw screen
+				UpdateSelectionInfo(); //mxd
 				General.Interface.RedrawDisplay();
 			}
 		}

Source/Plugins/BuilderModes/ClassicModes/VerticesMode.cs

@@ -936,6 +936,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			OnMouseMove(e);
 
 			// Redraw screen
+			UpdateSelectionInfo(); //mxd
 			General.Map.Renderer2D.UpdateExtraFloorFlag(); //mxd
 			General.Interface.RedrawDisplay();
 		}
@@ -1014,6 +1015,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			OnMouseMove(e);
 
 			// Redraw screen
+			UpdateSelectionInfo(); //mxd
 			General.Map.Renderer2D.UpdateExtraFloorFlag(); //mxd
 			General.Interface.RedrawDisplay();
 		}

Source/Plugins/SoundPropagationMode/BuilderPlug.cs

@@ -434,7 +434,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 
 		private static bool LinedefBlocksSoundEnvironment(Linedef linedef)
 		{
-			if(General.Map.UDMF) return linedef.IsFlagSet("zoneboundary"); //mxd. Fancier this way :)
+			if(General.Map.UDMF) return linedef.IsFlagSet(SoundEnvironmentMode.ZoneBoundaryFlag); //mxd. Fancier this way :)
 			
 			// In Hexen format the line must have action 121 (Line_SetIdentification) and bit 1 of
 			// the second argument set (see http://zdoom.org/wiki/Line_SetIdentification)

Source/Plugins/SoundPropagationMode/SoundEnvironmentMode.cs

@@ -62,6 +62,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 		#region ================== Properties
 
 		public override object HighlightedObject { get { return highlighted; } }
+		internal const string ZoneBoundaryFlag = "zoneboundary"; //mxd
 
 		#endregion
 
@@ -194,7 +195,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 			General.Map.UndoRedo.CreateUndo("Toggle Sound Zone Boundary");
 
 			// Toggle flag
-			highlightedline.SetFlag("zoneboundary", !highlightedline.IsFlagSet("zoneboundary"));
+			highlightedline.SetFlag(ZoneBoundaryFlag, !highlightedline.IsFlagSet(ZoneBoundaryFlag));
 
 			// Update
 			UpdateData();
@@ -385,7 +386,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 				//mxd. Find the nearest linedef within default highlight range
 				l = General.Map.Map.NearestLinedefRange(mousemappos, 20 / renderer.Scale);
 				//mxd. We are not interested in single-sided lines, unless they have zoneboundary flag...
-				if(l != null && ((l.Front == null || l.Back == null) && (General.Map.UDMF && !l.IsFlagSet("zoneboundary"))))
+				if(l != null && ((l.Front == null || l.Back == null) && (General.Map.UDMF && !l.IsFlagSet(ZoneBoundaryFlag))))
 				{
 					l = null;
 				}

Source/Plugins/SoundPropagationMode/SoundPropagationDomain.cs

@@ -56,7 +56,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 
 				foreach (Sidedef sd in sector.Sidedefs)
 				{
-					bool blocksound = sd.Line.IsFlagSet(General.Map.UDMF ? "blocksound" : "64");
+					bool blocksound = sd.Line.IsFlagSet(SoundPropagationMode.BlockSoundFlag);
 					if (blocksound) blockinglines.Add(sd.Line);
 
 					// If the line is one sided, the sound can travel nowhere, so try the next one

Source/Plugins/SoundPropagationMode/SoundPropagationMode.cs

@@ -57,6 +57,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 		#region ================== Properties
 
 		public override object HighlightedObject { get { return highlighted; } }
+		internal static string BlockSoundFlag { get { return (General.Map.UDMF ? "blocksound" : "64"); } } //mxd
 
 		#endregion
 
@@ -123,7 +124,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 			BuilderPlug.Me.BlockingLinedefs.Clear();
 
 			foreach (Linedef ld in General.Map.Map.Linedefs)
-				if (ld.IsFlagSet(General.Map.UDMF ? "blocksound" : "64"))
+				if (ld.IsFlagSet(BlockSoundFlag))
 					BuilderPlug.Me.BlockingLinedefs.Add(ld);
 
 			if (highlighted == null || highlighted.IsDisposed) return;
@@ -336,8 +337,7 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 			General.Map.UndoRedo.CreateUndo("Toggle Linedef Sound Blocking");
 
 			// Toggle flag
-			string flag = (General.Map.UDMF ? "blocksound" : "64");
+			highlightedline.SetFlag(BlockSoundFlag, !highlightedline.IsFlagSet(BlockSoundFlag));
-			highlightedline.SetFlag(flag, !highlightedline.IsFlagSet(flag));
 			
 			// Update
 			ResetSoundPropagation();
@@ -397,8 +397,8 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 
 				//mxd. Find the nearest linedef within default highlight range
 				l = General.Map.Map.NearestLinedefRange(mousemappos, 20 / renderer.Scale);
-				//mxd. We are not interested in single-sided lines...
+				//mxd. We are not interested in single-sided lines (unless they have "blocksound" flag set)...
-				if(l != null && (l.Front == null || l.Back == null)) l = null;
+				if(l != null && (l.Front == null || l.Back == null) && !l.IsFlagSet(BlockSoundFlag)) l = null;
 				
 				//mxd. Set as highlighted
 				if(highlightedline != l)

Source/Plugins/SoundPropagationMode/Windows/ReverbsPickerForm.Designer.cs

@@ -44,7 +44,7 @@
 			this.groupBox1.Size = new System.Drawing.Size(190, 351);
 			this.groupBox1.TabIndex = 0;
 			this.groupBox1.TabStop = false;
-			this.groupBox1.Text = " Sound Environments ";
+			this.groupBox1.Text = " Sound Environments: ";
 			// 
 			// list
 			// 
@@ -55,10 +55,12 @@
 			this.list.Size = new System.Drawing.Size(184, 329);
 			this.list.TabIndex = 0;
 			this.list.MouseDoubleClick += new System.Windows.Forms.MouseEventHandler(this.list_MouseDoubleClick);
+			this.list.SelectedIndexChanged += new System.EventHandler(this.list_SelectedIndexChanged);
 			// 
 			// accept
 			// 
 			this.accept.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
+			this.accept.Enabled = false;
 			this.accept.Location = new System.Drawing.Point(14, 394);
 			this.accept.Name = "accept";
 			this.accept.Size = new System.Drawing.Size(91, 23);

Source/Plugins/SoundPropagationMode/Windows/ReverbsPickerForm.cs

@@ -27,6 +27,8 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 			}
 		}
 
+		private static string previousenvironmentname;
+		
 		public ReverbsPickerForm(Thing t) 
 		{
 			InitializeComponent();
@@ -48,6 +50,19 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 				}
 			}
 
+			// Select previously selected item?
+			if(!string.IsNullOrEmpty(previousenvironmentname) && list.SelectedItem == null)
+			{
+				foreach(ReverbListItem item in list.Items)
+				{
+					if(item.ToString() == previousenvironmentname)
+					{
+						list.SelectedItem = item;
+						break;
+					}
+				}
+			}
+
 			// Dormant?
 			cbactiveenv.Checked = !BuilderPlug.ThingDormant(t);
 			list.Focus();
@@ -69,8 +84,14 @@ namespace CodeImp.DoomBuilder.SoundPropagationMode
 
 		private void accept_Click(object sender, EventArgs e) 
 		{
+			if(list.SelectedItem != null) previousenvironmentname = list.SelectedItem.ToString();
 			this.DialogResult = DialogResult.OK;
 			this.Close();
 		}
+
+		private void list_SelectedIndexChanged(object sender, EventArgs e)
+		{
+			accept.Enabled = (list.SelectedItem != null);
+		}
 	}
 }