Fixed a bug where selected lines were deselected when trying to find/replace

Replacing can now be made undone

Source/Plugins/BuilderModes/ClassicModes/FindReplaceMode.cs

@@ -89,10 +89,13 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			// Select linedefs by sectors
 			foreach(Linedef ld in General.Map.Map.Linedefs)
 			{
-				bool front, back;
-				if(ld.Front != null) front = ld.Front.Sector.Selected; else front = false;
-				if(ld.Back != null) back = ld.Back.Sector.Selected; else back = false;
-				ld.Selected = front | back;
+				if (ld.Selected == false)
+				{
+					bool front, back;
+					if (ld.Front != null) front = ld.Front.Sector.Selected; else front = false;
+					if (ld.Back != null) back = ld.Back.Sector.Selected; else back = false;
+					ld.Selected = front | back;
+				}
 			}
 			
 			// Show toolbox window

Source/Plugins/BuilderModes/Interface/FindReplaceForm.cs

@@ -169,8 +169,16 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			// Perform the search / replace and show the results
 			if(doreplace.Checked)
 			{
+				int ticket = General.Map.UndoRedo.CreateUndo("Replace " + searchtypes.SelectedItem);
+
 				resultslist.Items.AddRange(finder.Find(findinput.Text, withinselection.Checked, replaceinput.Text, false));
 				resultscount.Text = resultslist.Items.Count + " items found and replaced.";
+
+				// Withdraw the undo step if nothing was replaced
+				if (resultslist.Items.Count <= 0)
+				{
+					General.Map.UndoRedo.WithdrawUndo(ticket);
+				}
 			}
 			else
 			{