display document open error message

dialog.lua

@@ -10,6 +10,7 @@ function InfoMessage:show(text)
 		dimen = { w = G_width, h = G_height },
 		FrameContainer:new({
 			margin = 2,
+			background = 0,
 			HorizontalGroup:new({
 				align = "center",
 				ImageWidget:new({

reader.lua

@@ -26,6 +26,7 @@ require "settings"
 require "screen"
 require "keys"
 require "commands"
+require "dialog"
 
 -- option parsing:
 longopts = {
@@ -55,7 +56,9 @@ function openFile(filename)
 			reader_settings:savesetting("lastfile", filename)
 			return reader:inputLoop()
 		else
-			-- TODO: error handling
+			InfoMessage:show("Error opening document.")
+			fb:refresh(0)
+			util.sleep(2)
 		end
 	end
 	return true -- on failed attempts, we signal to keep running