InputContainer/FocusManager: Simplify key_events clearing on unplug

Thanks to @poire-z for the idea, it's indeed much nicer this way ;).

frontend/apps/filemanager/filemanager.lua

@@ -473,7 +473,7 @@ function FileManager:setupLayout()
 end
 
 function FileManager:registerKeyEvents()
-    -- NOTE: There's no init vs. runtime distinction here, because we go through reinit at runtime.
+    -- NOTE: We need to be surgical here, because this is called through reinit at runtime.
     if Device:hasKeys() then
         self.key_events.Home = { { "Home" } }
         -- Override the menu.lua way of handling the back key

frontend/apps/filemanager/filemanagermenu.lua

@@ -48,7 +48,7 @@ function FileManagerMenu:init()
 
     self.registered_widgets = {}
 
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     self.activation_menu = G_reader_settings:readSetting("activate_menu")
     if self.activation_menu == nil then
@@ -56,16 +56,13 @@ function FileManagerMenu:init()
     end
 end
 
-function FileManagerMenu:registerKeyEvents(init)
+function FileManagerMenu:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events.ShowMenu = { { "Menu" } }
-    elseif not init then
-        self.key_events.ShowMenu = nil
     end
 end
 
 FileManagerMenu.onPhysicalKeyboardConnected = FileManagerMenu.registerKeyEvents
-FileManagerMenu.onPhysicalKeyboardDisconnected = FileManagerMenu.registerKeyEvents
 
 function FileManagerMenu:initGesListener()
     if not Device:isTouchDevice() then return end

frontend/apps/reader/modules/readerback.lua

@@ -20,7 +20,7 @@ local ReaderBack = EventListener:extend{
 }
 
 function ReaderBack:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     -- Regular function wrapping our method, to avoid re-creating
     -- an anonymous function at each page turn
     self._addPreviousLocationToStackCallback = function()
@@ -28,16 +28,13 @@ function ReaderBack:init()
     end
 end
 
-function ReaderBack:registerKeyEvents(init)
+function ReaderBack:registerKeyEvents()
     if Device:hasKeys() then
         self.ui.key_events.Back = { { Device.input.group.Back } }
-    elseif not init then
-        self.ui.key_events.Back = nil
     end
 end
 
 ReaderBack.onPhysicalKeyboardConnected = ReaderBack.registerKeyEvents
-ReaderBack.onPhysicalKeyboardDisconnected = ReaderBack.registerKeyEvents
 
 function ReaderBack:_getCurrentLocation()
     if self.ui.document.info.has_pages then

frontend/apps/reader/modules/readerbookmark.lua

@@ -37,7 +37,7 @@ local ReaderBookmark = InputContainer:extend{
 }
 
 function ReaderBookmark:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     if G_reader_settings:hasNot("bookmarks_items_per_page") then
         -- The Bookmarks items per page and items' font size can now be
@@ -60,16 +60,13 @@ end
 
 function ReaderBookmark:onGesture() end
 
-function ReaderBookmark:registerKeyEvents(init)
+function ReaderBookmark:registerKeyEvents()
     if Device:hasKeyboard() then
         self.key_events.ShowBookmark = { { "B" } }
-    elseif not init then
-        self.key_events.ShowBookmark = nil
     end
 end
 
 ReaderBookmark.onPhysicalKeyboardConnected = ReaderBookmark.registerKeyEvents
-ReaderBookmark.onPhysicalKeyboardDisconnected = ReaderBookmark.registerKeyEvents
 
 function ReaderBookmark:addToMainMenu(menu_items)
     menu_items.bookmarks = {

frontend/apps/reader/modules/readerconfig.lua

@@ -19,7 +19,7 @@ function ReaderConfig:init()
     end
     self.configurable:loadDefaults(self.options)
 
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     self:initGesListener()
     if G_reader_settings:has("activate_menu") then
         self.activation_menu = G_reader_settings:readSetting("activate_menu")
@@ -33,16 +33,13 @@ end
 
 function ReaderConfig:onGesture() end
 
-function ReaderConfig:registerKeyEvents(init)
+function ReaderConfig:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events.ShowConfigMenu = { { { "Press", "AA" } } }
-    elseif not init then
-        self.key_events.ShowConfigMenu = nil
     end
 end
 
 ReaderConfig.onPhysicalKeyboardConnected = ReaderConfig.registerKeyEvents
-ReaderConfig.onPhysicalKeyboardDisconnected = ReaderConfig.registerKeyEvents
 
 function ReaderConfig:initGesListener()
     if not Device:isTouchDevice() then return end

frontend/apps/reader/modules/readerfont.lua

@@ -31,7 +31,7 @@ local ReaderFont = InputContainer:extend{
 }
 
 function ReaderFont:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     -- Build face_table for menu
     self.face_table = {}
     -- Font settings
@@ -118,7 +118,7 @@ end
 
 function ReaderFont:onGesture() end
 
-function ReaderFont:registerKeyEvents(init)
+function ReaderFont:registerKeyEvents()
     if Device:hasKeyboard() then
         -- add shortcut for keyboard
         self.key_events = {
@@ -134,13 +134,10 @@ function ReaderFont:registerKeyEvents(init)
                 args = -0.5
             },
         }
-    elseif not init then
-        self.key_events = {}
     end
 end
 
 ReaderFont.onPhysicalKeyboardConnected = ReaderFont.registerKeyEvents
-ReaderFont.onPhysicalKeyboardDisconnected = ReaderFont.registerKeyEvents
 
 function ReaderFont:onSetDimensions(dimen)
     self.dimen = dimen

frontend/apps/reader/modules/readerhighlight.lua

@@ -52,7 +52,7 @@ function ReaderHighlight:init()
     self._previous_indicator_pos = nil
     self._last_indicator_move_args = {dx = 0, dy = 0, distance = 0, time = time:now()}
 
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     self._highlight_buttons = {
         -- highlight and add_note are for the document itself,
@@ -220,41 +220,28 @@ end
 
 function ReaderHighlight:onGesture() end
 
-function ReaderHighlight:registerKeyEvents(init)
-    if Device:hasDPad() then
+function ReaderHighlight:registerKeyEvents()
+    if Device:hasKeys() then
         -- Used for text selection with dpad/keys
         local QUICK_INDICATOR_MOVE = true
-        self.key_events.StopHighlightIndicator  = { { Device.input.group.Back }, args = true } -- true: clear highlight selection
-        self.key_events.UpHighlightIndicator    = { { "Up" },    event = "MoveHighlightIndicator", args = {0, -1} }
-        self.key_events.DownHighlightIndicator  = { { "Down" },  event = "MoveHighlightIndicator", args = {0, 1} }
-        -- let FewKeys device can move indicator left
-        self.key_events.LeftHighlightIndicator  = { { "Left" },  event = "MoveHighlightIndicator", args = {-1, 0} }
-        self.key_events.RightHighlightIndicator = { { "Right" }, event = "MoveHighlightIndicator", args = {1, 0} }
-        self.key_events.HighlightPress          = { { "Press" } }
-        if Device:hasKeys() then
-            self.key_events.QuickUpHighlightIndicator    = { { "Shift", "Up" },    event = "MoveHighlightIndicator", args = {0, -1, QUICK_INDICATOR_MOVE} }
-            self.key_events.QuickDownHighlightIndicator  = { { "Shift", "Down" },  event = "MoveHighlightIndicator", args = {0, 1, QUICK_INDICATOR_MOVE} }
-            self.key_events.QuickLeftHighlightIndicator  = { { "Shift", "Left" },  event = "MoveHighlightIndicator", args = {-1, 0, QUICK_INDICATOR_MOVE} }
-            self.key_events.QuickRightHighlightIndicator = { { "Shift", "Right" }, event = "MoveHighlightIndicator", args = {1, 0, QUICK_INDICATOR_MOVE} }
-            self.key_events.StartHighlightIndicator      = { { "H" } }
+        self.key_events.QuickUpHighlightIndicator    = { { "Shift", "Up" },    event = "MoveHighlightIndicator", args = {0, -1, QUICK_INDICATOR_MOVE} }
+        self.key_events.QuickDownHighlightIndicator  = { { "Shift", "Down" },  event = "MoveHighlightIndicator", args = {0, 1, QUICK_INDICATOR_MOVE} }
+        self.key_events.QuickLeftHighlightIndicator  = { { "Shift", "Left" },  event = "MoveHighlightIndicator", args = {-1, 0, QUICK_INDICATOR_MOVE} }
+        self.key_events.QuickRightHighlightIndicator = { { "Shift", "Right" }, event = "MoveHighlightIndicator", args = {1, 0, QUICK_INDICATOR_MOVE} }
+        self.key_events.StartHighlightIndicator      = { { "H" } }
+        if Device:hasDPad() then
+            self.key_events.StopHighlightIndicator  = { { Device.input.group.Back }, args = true } -- true: clear highlight selection
+            self.key_events.UpHighlightIndicator    = { { "Up" },    event = "MoveHighlightIndicator", args = {0, -1} }
+            self.key_events.DownHighlightIndicator  = { { "Down" },  event = "MoveHighlightIndicator", args = {0, 1} }
+            -- let hasFewKeys device move the indicator left
+            self.key_events.LeftHighlightIndicator  = { { "Left" },  event = "MoveHighlightIndicator", args = {-1, 0} }
+            self.key_events.RightHighlightIndicator = { { "Right" }, event = "MoveHighlightIndicator", args = {1, 0} }
+            self.key_events.HighlightPress          = { { "Press" } }
         end
-    elseif not init then
-        self.key_events.StopHighlightIndicator  = nil
-        self.key_events.UpHighlightIndicator    = nil
-        self.key_events.DownHighlightIndicator  = nil
-        self.key_events.LeftHighlightIndicator  = nil
-        self.key_events.RightHighlightIndicator = nil
-        self.key_events.HighlightPress          = nil
-        self.key_events.QuickUpHighlightIndicator    = nil
-        self.key_events.QuickDownHighlightIndicator  = nil
-        self.key_events.QuickLeftHighlightIndicator  = nil
-        self.key_events.QuickRightHighlightIndicator = nil
-        self.key_events.StartHighlightIndicator      = nil
     end
 end
 
 ReaderHighlight.onPhysicalKeyboardConnected = ReaderHighlight.registerKeyEvents
-ReaderHighlight.onPhysicalKeyboardDisconnected = ReaderHighlight.registerKeyEvents
 
 function ReaderHighlight:setupTouchZones()
     if not Device:isTouchDevice() then return end

frontend/apps/reader/modules/readerlink.lua

@@ -26,7 +26,7 @@ local ReaderLink = InputContainer:extend{
 }
 
 function ReaderLink:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     if Device:isTouchDevice() then
         self.ui:registerTouchZones({
             {
@@ -95,7 +95,7 @@ end
 
 function ReaderLink:onGesture() end
 
-function ReaderLink:registerKeyEvents(init)
+function ReaderLink:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events = {
             SelectNextPageLink = {
@@ -114,13 +114,10 @@ function ReaderLink:registerKeyEvents(init)
             -- "Back" is handled by ReaderBack, which will call our onGoBackLink()
             -- when G_reader_settings:readSetting("back_in_reader") == "previous_location"
         }
-    elseif not init then
-        self.key_events = {}
     end
 end
 
 ReaderLink.onPhysicalKeyboardConnected = ReaderLink.registerKeyEvents
-ReaderLink.onPhysicalKeyboardDisconnected = ReaderLink.registerKeyEvents
 
 function ReaderLink:onReadSettings(config)
     -- called when loading new document

frontend/apps/reader/modules/readermenu.lua

@@ -56,7 +56,7 @@ function ReaderMenu:init()
 
     self.registered_widgets = {}
 
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     if G_reader_settings:has("activate_menu") then
         self.activation_menu = G_reader_settings:readSetting("activate_menu")
@@ -70,7 +70,7 @@ end
 
 function ReaderMenu:onGesture() end
 
-function ReaderMenu:registerKeyEvents(init)
+function ReaderMenu:registerKeyEvents()
     if Device:hasKeys() then
         if Device:isTouchDevice() then
             self.key_events.TapShowMenu = { { "Menu" } }
@@ -85,14 +85,10 @@ function ReaderMenu:registerKeyEvents(init)
                 self.key_events.ShowMenu = { { { "Menu", "Right" } } }
             end
         end
-    elseif not init then
-        self.key_events.TapShowMenu = nil
-        self.key_events.ShowMenu = nil
     end
 end
 
 ReaderMenu.onPhysicalKeyboardConnected = ReaderMenu.registerKeyEvents
-ReaderMenu.onPhysicalKeyboardDisconnected = ReaderMenu.registerKeyEvents
 
 function ReaderMenu:getPreviousFile()
     return require("readhistory"):getPreviousFile(self.ui.document.file)

frontend/apps/reader/modules/readerpaging.lua

@@ -41,7 +41,7 @@ local ReaderPaging = InputContainer:extend{
 }
 
 function ReaderPaging:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     self.pan_interval = time.s(1 / self.pan_rate)
     self.number_of_pages = self.ui.document.info.number_of_pages
 
@@ -51,7 +51,7 @@ end
 
 function ReaderPaging:onGesture() end
 
-function ReaderPaging:registerKeyEvents(init)
+function ReaderPaging:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events.GotoNextPage = {
             { { "RPgFwd", "LPgFwd", not Device:hasFewKeys() and "Right" } },
@@ -73,11 +73,6 @@ function ReaderPaging:registerKeyEvents(init)
             event = "GotoPosRel",
             args = -1,
         }
-    elseif not init then
-        self.key_events.GotoNextPage = nil
-        self.key_events.GotoPrevPage = nil
-        self.key_events.GotoNextPos = nil
-        self.key_events.GotoPrevPos = nil
     end
     if Device:hasKeyboard() then
         self.key_events.GotoFirst = {
@@ -130,22 +125,10 @@ function ReaderPaging:registerKeyEvents(init)
             event = "GotoPercent",
             args = 100,
         }
-    elseif not init then
-        self.key_events.GotoFirst = nil
-        self.key_events.Goto11 = nil
-        self.key_events.Goto22 = nil
-        self.key_events.Goto33 = nil
-        self.key_events.Goto44 = nil
-        self.key_events.Goto55 = nil
-        self.key_events.Goto66 = nil
-        self.key_events.Goto77 = nil
-        self.key_events.Goto88 = nil
-        self.key_events.GotoLast = nil
     end
 end
 
 ReaderPaging.onPhysicalKeyboardConnected = ReaderPaging.registerKeyEvents
-ReaderPaging.onPhysicalKeyboardDisconnected = ReaderPaging.registerKeyEvents
 
 function ReaderPaging:onReaderReady()
     self:setupTouchZones()

frontend/apps/reader/modules/readerpanning.lua

@@ -13,14 +13,14 @@ local ReaderPanning = InputContainer:extend{
 }
 
 function ReaderPanning:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     -- NOP our own gesture handling
     self.ges_events = nil
 end
 
 function ReaderPanning:onGesture() end
 
-function ReaderPanning:registerKeyEvents(init)
+function ReaderPanning:registerKeyEvents()
     if Device:hasKeyboard() then
         self.key_events = {
             -- these will all generate the same event, just with different arguments
@@ -45,13 +45,10 @@ function ReaderPanning:registerKeyEvents(init)
                 args = {1,  0}
             },
         }
-    elseif not init then
-        self.key_events = {}
     end
 end
 
 ReaderPanning.onPhysicalKeyboardConnected = ReaderPanning.registerKeyEvents
-ReaderPanning.onPhysicalKeyboardDisconnected = ReaderPanning.registerKeyEvents
 
 function ReaderPanning:onPanning(args, _)
     local dx, dy = unpack(args)

frontend/apps/reader/modules/readerrolling.lua

@@ -57,7 +57,7 @@ local ReaderRolling = InputContainer:extend{
 }
 
 function ReaderRolling:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     self.pan_interval = time.s(1 / self.pan_rate)
 
     table.insert(self.ui.postInitCallback, function()
@@ -79,7 +79,7 @@ end
 
 function ReaderRolling:onGesture() end
 
-function ReaderRolling:registerKeyEvents(init)
+function ReaderRolling:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events.GotoNextView = {
             { { "RPgFwd", "LPgFwd", "Right" } },
@@ -91,9 +91,6 @@ function ReaderRolling:registerKeyEvents(init)
             event = "GotoViewRel",
             args = -1,
         }
-    elseif not init then
-        self.key_events.GotoNextView = nil
-        self.key_events.GotoPrevView = nil
     end
     if Device:hasDPad() then
         self.key_events.MoveUp = {
@@ -106,9 +103,6 @@ function ReaderRolling:registerKeyEvents(init)
             event = "Panning",
             args = {0,  1},
         }
-    elseif not init then
-        self.key_events.MoveUp = nil
-        self.key_events.MoveDown = nil
     end
     if Device:hasKeyboard() then
         self.key_events.GotoFirst = {
@@ -161,22 +155,10 @@ function ReaderRolling:registerKeyEvents(init)
             event = "GotoPercent",
             args = 100,
         }
-    elseif not init then
-        self.key_events.GotoFirst = nil
-        self.key_events.Goto11 = nil
-        self.key_events.Goto22 = nil
-        self.key_events.Goto33 = nil
-        self.key_events.Goto44 = nil
-        self.key_events.Goto55 = nil
-        self.key_events.Goto66 = nil
-        self.key_events.Goto77 = nil
-        self.key_events.Goto88 = nil
-        self.key_events.GotoLast = nil
     end
 end
 
 ReaderRolling.onPhysicalKeyboardConnected = ReaderRolling.registerKeyEvents
-ReaderRolling.onPhysicalKeyboardDisconnected = ReaderRolling.registerKeyEvents
 
 function ReaderRolling:onReadSettings(config)
     -- 20180503: some fix in crengine has changed the way the DOM is built

frontend/apps/reader/modules/readerrotation.lua

@@ -8,14 +8,14 @@ local ReaderRotation = InputContainer:extend{
 }
 
 function ReaderRotation:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
     -- NOP our own gesture handling
     self.ges_events = nil
 end
 
 function ReaderRotation:onGesture() end
 
-function ReaderRotation:registerKeyEvents(init)
+function ReaderRotation:registerKeyEvents()
     if Device:hasKeyboard() then
         self.key_events = {
             -- these will all generate the same event, just with different arguments
@@ -30,13 +30,10 @@ function ReaderRotation:registerKeyEvents(init)
                 args = 90
             },
         }
-    elseif not init then
-        self.key_events = {}
     end
 end
 
 ReaderRotation.onPhysicalKeyboardConnected = ReaderRotation.registerKeyEvents
-ReaderRotation.onPhysicalKeyboardDisconnected = ReaderRotation.registerKeyEvents
 
 --- @todo Reset rotation on new document, maybe on new page?
 

frontend/apps/reader/modules/readerstyletweak.lua

@@ -50,7 +50,7 @@ function TweakInfoWidget:init()
             }
         }
     end
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     local content = VerticalGroup:new{
         TextBoxWidget:new{
@@ -166,16 +166,13 @@ function TweakInfoWidget:init()
     }
 end
 
-function TweakInfoWidget:registerKeyEvents(init)
+function TweakInfoWidget:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events.Close = { { Device.input.group.Back } }
-    elseif not init then
-        self.key_events.Close = nil
     end
 end
 
 TweakInfoWidget.onPhysicalKeyboardConnected = TweakInfoWidget.registerKeyEvents
-TweakInfoWidget.onPhysicalKeyboardDisconnected = TweakInfoWidget.registerKeyEvents
 
 function TweakInfoWidget:onShow()
     UIManager:setDirty(self, function()

frontend/apps/reader/modules/readertoc.lua

@@ -35,7 +35,7 @@ local ReaderToc = InputContainer:extend{
 }
 
 function ReaderToc:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     if G_reader_settings:hasNot("toc_items_per_page") then
         -- The TOC items per page and items' font size can now be
@@ -60,16 +60,13 @@ end
 
 function ReaderToc:onGesture() end
 
-function ReaderToc:registerKeyEvents(init)
+function ReaderToc:registerKeyEvents()
     if Device:hasKeyboard() then
         self.key_events.ShowToc = { { "T" } }
-    elseif not init then
-        self.key_events.ShowToc = nil
     end
 end
 
 ReaderToc.onPhysicalKeyboardConnected = ReaderToc.registerKeyEvents
-ReaderToc.onPhysicalKeyboardDisconnected = ReaderToc.registerKeyEvents
 
 function ReaderToc:onReadSettings(config)
     self.toc_ticks_ignored_levels = config:readSetting("toc_ticks_ignored_levels") or {}

frontend/apps/reader/modules/readerzooming.lua

@@ -91,10 +91,10 @@ local ReaderZooming = InputContainer:extend{
 }
 
 function ReaderZooming:init()
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 end
 
-function ReaderZooming:registerKeyEvents(init)
+function ReaderZooming:registerKeyEvents()
     if Device:hasKeyboard() then
         self.key_events = {
             ZoomIn = {
@@ -143,13 +143,10 @@ function ReaderZooming:registerKeyEvents(init)
                 args = "manual",
             },
         }
-    elseif not init then
-        self.key_events = {}
     end
 end
 
 ReaderZooming.onPhysicalKeyboardConnected = ReaderZooming.registerKeyEvents
-ReaderZooming.onPhysicalKeyboardDisconnected = ReaderZooming.registerKeyEvents
 
 -- Conversions between genus/type combos and zoom_mode...
 function ReaderZooming:mode_to_combo(zoom_mode)

frontend/apps/reader/readerui.lua

@@ -122,7 +122,7 @@ function ReaderUI:init()
     -- Handle local settings migration
     SettingsMigration:migrateSettings(self.doc_settings)
 
-    self:registerKeyEvents(true)
+    self:registerKeyEvents()
 
     -- a view container (so it must be child #1!)
     -- all paintable widgets need to be a child of reader view
@@ -481,18 +481,14 @@ function ReaderUI:init()
     ReaderUI.instance = self
 end
 
-function ReaderUI:registerKeyEvents(init)
+function ReaderUI:registerKeyEvents()
     if Device:hasKeys() then
         self.key_events.Home = { { "Home" } }
         self.key_events.Reload = { { "F5" } }
-    elseif not init then
-        self.key_events.Home = nil
-        self.key_events.Reload = nil
     end
 end
 
 ReaderUI.onPhysicalKeyboardConnected = ReaderUI.registerKeyEvents
-ReaderUI.onPhysicalKeyboardDisconnected = ReaderUI.registerKeyEvents
 
 function ReaderUI:setLastDirForFileBrowser(dir)
     if dir and #dir > 1 and dir:sub(-1) == "/" then

frontend/ui/widget/container/inputcontainer.lua

@@ -305,4 +305,13 @@ function InputContainer:closeInputDialog()
     UIManager:close(self.input_dialog)
 end
 
+function InputContainer:onPhysicalKeyboardDisconnected()
+    -- Clear the key bindings if Device no longer has keys
+    -- NOTE: hasKeys is the lowest common denominator of key-related Device caps,
+    --       hasDPad/hasFewKeys/hasKeyboard all imply hasKeys ;).
+    if not Device:hasKeys() then
+        self.key_events = {}
+    end
+end
+
 return InputContainer

frontend/ui/widget/focusmanager.lua

@@ -274,12 +274,17 @@ function FocusManager:onPhysicalKeyboardDisconnected()
     local prev_key_events = KEY_EVENTS
     populateEventMappings()
 
-    -- Remove what disappeared from KEY_EVENTS from self.key_events (if any).
-    -- NOTE: This is slightly overkill, we could very well live with a few unreachable mappings for the rest of this widget's life ;).
-    for k, _ in pairs(prev_key_events) do
-        if not KEY_EVENTS[k] then
-            self.key_events[k] = nil
+    -- If we still have keys, remove what disappeared from KEY_EVENTS from self.key_events (if any).
+    if Device:hasKeys() then
+        -- NOTE: This is slightly overkill, we could very well live with a few unreachable mappings for the rest of this widget's life ;).
+        for k, _ in pairs(prev_key_events) do
+            if not KEY_EVENTS[k] then
+                self.key_events[k] = nil
+            end
         end
+    else
+        -- If we longer have keys at all, that's easy ;).
+        self.key_events = {}
     end
     self.builtin_key_events = BUILTIN_KEY_EVENTS
     self.extra_key_events = EXTRA_KEY_EVENTS