Added Esc key to close top-left GUI and fixed issue where you could be typing into the notepad when it's closed.

control.lua

@@ -426,3 +426,12 @@ script.on_event(defines.events.on_gui_text_changed, function(event)
     NotepadOnGuiTextChange(event)
     SharedElectricityPlayerGuiValueChange(event)
 end)
+
+
+----------------------------------------
+-- On Gui Closed
+-- For capturing player escaping custom GUI so we can close it using ESC key.
+----------------------------------------
+script.on_event(defines.events.on_gui_closed, function(event)
+    OarcGuiOnGuiClosedEvent(event)
+end)

lib/oarc_gui_tabs.lua

@@ -79,10 +79,18 @@ function DoesOarcGuiExist(player)
     return (mod_gui.get_frame_flow(player)[OARC_GUI] ~= nil)
 end
 
+function IsOarcGuiVisible(player)
+    local of = mod_gui.get_frame_flow(player)[OARC_GUI]
+    return (of.visible)
+end
+
 function ToggleOarcGuiVisible(player)
     local of = mod_gui.get_frame_flow(player)[OARC_GUI]
     if (of ~= nil) then
         of.visible = not of.visible
+        if (of.visible) then
+            player.opened = of -- This allows us to indicate the player has this GUI open and when they press Esc we'll get an event!
+        end
     end
 end
 
@@ -111,8 +119,10 @@ function ClickOarcGuiButton(event)
         CreateOarcGuiTabsPane(player)
     else
         ToggleOarcGuiVisible(player)
+        if (IsOarcGuiVisible(player)) then
             FakeTabChangeEventOarcGui(player)
         end
+    end
 end
 
 function TabChangeOarcGui(event)
@@ -265,3 +275,9 @@ function SwitchOarcGuiTab(player, tab_name)
         end
     end
 end
+
+function OarcGuiOnGuiClosedEvent(event)
+    if (event.element.name == "oarc_gui") then
+        ToggleOarcGuiVisible(game.players[event.player_index])
+    end
+end