widgets inherit from Panel and can be perma-enabled

docs/dev/Lua API.rst

@@ -4154,6 +4154,8 @@ Base of all the widgets. Inherits from View and has the following attributes:
 
   The pen to fill the outer frame with. Defaults to no fill.
 
+.. _panel:
+
 Panel class
 -----------
 

docs/dev/overlay-dev-guide.rst

@@ -38,7 +38,7 @@ Overlay widget API
 ------------------
 
 Overlay widgets are Lua classes that inherit from ``overlay.OverlayWidget``
-(which itself inherits from `widgets.Widget <widget>`). The regular
+(which itself inherits from `widgets.Panel <panel>`). The regular
 ``onInput(keys)``, ``onRenderFrame(dc, frame_rect)``, and ``onRenderBody(dc)``
 functions work as normal, and they are called when the viewscreen that the
 widget is associated with does its usual input and render processing. The widget
@@ -125,6 +125,10 @@ The ``overlay.OverlayWidget`` superclass defines the following class attributes:
     not annoy the player. Set to 0 to be called at the maximum rate. Be aware
     that running more often than you really need to will impact game FPS,
     especially if your widget can run while the game is unpaused.
+- ``always_enabled`` (default: ``false``)
+    Set this to ``true`` if you don't want to let the user disable the widget.
+    This is useful for widgets that are controlled purely through their
+    triggers. See `gui/pathable` for an example.
 
 Registering a widget with the overlay framework
 ***********************************************

plugins/lua/overlay.lua

@@ -177,6 +177,7 @@ end
 
 local function do_disable(args, quiet)
     local disable_fn = function(name, db_entry)
+        if db_entry.widget.always_enabled then return end
         overlay_config[name].enabled = false
         if db_entry.widget.hotspot then
             active_hotspot_widgets[name] = nil
@@ -244,7 +245,7 @@ local function load_widget(name, widget_class)
     local config = overlay_config[name]
     config.pos = sanitize_pos(config.pos or widget.default_pos)
     widget.frame = make_frame(config.pos, widget.frame)
-    if config.enabled then
+    if config.enabled or widget.always_enabled then
         do_enable(name, true, true)
     else
         config.enabled = false
@@ -461,7 +462,7 @@ end
 -- OverlayWidget (base class of all overlay widgets) --
 -- ------------------------------------------------- --
 
-OverlayWidget = defclass(OverlayWidget, widgets.Widget)
+OverlayWidget = defclass(OverlayWidget, widgets.Panel)
 OverlayWidget.ATTRS{
     name=DEFAULT_NIL, -- this is set by the framework to the widget name
     default_pos={x=DEFAULT_X_POS, y=DEFAULT_Y_POS}, -- 1-based widget screen pos
@@ -469,6 +470,7 @@ OverlayWidget.ATTRS{
     hotspot=false, -- whether to call overlay_onupdate on all screens
     viewscreens={}, -- override with associated viewscreen or list of viewscrens
     overlay_onupdate_max_freq_seconds=5, -- throttle calls to overlay_onupdate
+    always_enabled=false, -- for overlays that should never be disabled
 }
 
 function OverlayWidget:init()