Display code points for incompatible whitespaces

CHANGELOG.md

@@ -22,6 +22,7 @@ Change Log
 - Update document icons.
 - Detect the line ending in documents more intelligently.
 - Rename the Incompatible Characters pane to the Warnings pane to share the pane with the inconsistent line ending list.
+- Display code points instead of left blank in the incompatible character list for whitespaces.
 - Locate the vertical scroller for the editor on the left side when the writing direction is right-to-left.
 - Print the line numbers on the right side on printing if the writing direction is right-to-left.
 - Adjust the vertical position of line numbers on printing. 

CotEditor/Sources/IncompatibleCharacterFormatter.swift

@@ -28,6 +28,10 @@ import AppKit.NSColor
 
 final class IncompatibleCharacterFormatter: Formatter {
     
+    private let invisibleCategories: Set<Unicode.GeneralCategory> = [.control, .spaceSeparator, .lineSeparator]
+    
+    
+    
     // MARK: Formatter Function
     
     /// convert to plain string
@@ -44,7 +48,7 @@ final class IncompatibleCharacterFormatter: Formatter {
             let string = self.string(for: obj),
             string.unicodeScalars.compareCount(with: 1) == .equal,
             let unicode = string.unicodeScalars.first,
-            unicode.properties.generalCategory == .control
+            self.invisibleCategories.contains(unicode.properties.generalCategory)
         else { return nil }
         
         let attributes = (attrs ?? [:]).merging([.foregroundColor: NSColor.tertiaryLabelColor]) { $1 }