DictQuickLookup: update to TitleBar widget

Also tweak ReaderHighlight:onHoldRelease() to avoid
doing its stuff when onHold() is clearing highlight
(previous CheckButton was closing/clearing on hold
release, new TitleBar close button does that on hold).

frontend/apps/reader/modules/readerhighlight.lua

@@ -1327,6 +1327,14 @@ function ReaderHighlight:onTranslateText(text)
 end
 
 function ReaderHighlight:onHoldRelease()
+    if self.clear_id then
+        -- Something has requested a clear id and is about to clear
+        -- the highlight: it may be a onHoldClose() that handled
+        -- "hold" and was closed, and can't handle "hold_release":
+        -- ignore this "hold_release" event.
+        return true
+    end
+
     local default_highlight_action = G_reader_settings:readSetting("default_highlight_action", "ask")
 
     if self.select_mode then -- extended highlighting, ending fragment