Address PR comments, and remove BG fill

BG fill eats up a lot of cycles anyway, and there's not a real tangible
benefit in all cases, as it relies on the text label being sized
appropriately (width-wise) to the container, or would otherwise require
padding.

docs/dev/Lua API.rst

@@ -4662,7 +4662,9 @@ It has the following attributes:
 
 :text_pen: Specifies the pen for active text.
 :text_dpen: Specifies the pen for disabled text.
-:text_hpen: Specifies the pen for text hovered over by the mouse, if a click handler is registered.
+:text_hpen: Specifies the pen for text hovered over by the mouse, if a click
+            handler is registered. By default, this will invert the foreground
+            and background colors.
 :disabled: Boolean or a callback; if true, the label is disabled.
 :enabled: Boolean or a callback; if false, the label is disabled.
 :auto_height: Sets self.frame.h from the text height.
@@ -4769,6 +4771,18 @@ The Label widget implements the following methods:
   ``+halfpage``, ``-halfpage``, ``home``, or ``end``. It returns the number of
   lines that were actually scrolled (negative for scrolling up).
 
+* ``label:shouldHover()``
+
+  This method returns whether or not this widget should show a hover effect,
+  generally you want to return ``true`` if there is some type of mouse handler
+  present. For example, for a ``HotKeyLabel``::
+
+    function HotkeyLabel:shouldHover()
+        -- When on_activate is set, text should also hover on mouseover
+        return HotkeyLabel.super.shouldHover(self) or self.on_activate
+    end
+
+
 WrappedLabel class
 ------------------
 

library/lua/gui/widgets.lua

@@ -1232,7 +1232,7 @@ Label = defclass(Label, Widget)
 Label.ATTRS{
     text_pen = COLOR_WHITE,
     text_dpen = COLOR_DARKGREY, -- disabled
-    text_hpen = DEFAULT_NIL, -- highlight - default is text_pen with reversed brightness
+    text_hpen = DEFAULT_NIL, -- hover - default is to invert the fg/bg colors
     disabled = DEFAULT_NIL,
     enabled = DEFAULT_NIL,
     auto_height = true,
@@ -1250,8 +1250,6 @@ function Label:init(args)
     self:addviews{self.scrollbar}
 
     self:setText(args.text or self.text)
-
-    -- self.text_hpen = make_hpen(self.text_pen, self.text_hpen)
 end
 
 local function update_label_scrollbar(label)
@@ -1305,15 +1303,6 @@ function Label:shouldHover()
     return self.on_click or self.on_rclick
 end
 
-function Label:onRenderFrame(dc, rect)
-    Label.super.onRenderFrame(self, dc, rect)
-    -- Fill the background with text_hpen on hover
-    if self:getMousePos() and self:shouldHover() then
-        local hpen = make_hpen(self.text_pen, self.text_hpen)
-        dc:fill(rect, hpen)
-    end
-end
-
 function Label:onRenderBody(dc)
     local text_pen = self.text_pen
     local hovered = self:getMousePos() and self:shouldHover()
@@ -1614,7 +1603,7 @@ List = defclass(List, Widget)
 
 List.ATTRS{
     text_pen = COLOR_CYAN,
-    text_hpen = DEFAULT_NIL, -- pen to render list item when mouse is hovered over; defaults to text_pen with inverted brightness
+    text_hpen = DEFAULT_NIL, -- hover color, defaults to inverting the FG/BG pens for each text object
     cursor_pen = COLOR_LIGHTCYAN,
     inactive_pen = DEFAULT_NIL,
     on_select = DEFAULT_NIL,
@@ -1644,8 +1633,6 @@ function List:init(info)
     end
 
     self.last_select_click_ms = 0 -- used to track double-clicking on an item
-
-    -- self.text_hpen = make_hpen(self.text_pen, self.text_hpen)
 end
 
 function List:setChoices(choices, selected)