diff --git a/docs/dev/Lua API.rst b/docs/dev/Lua API.rst
index 8c9655b69..a3b91af18 100644
--- a/docs/dev/Lua API.rst	
+++ b/docs/dev/Lua API.rst	
@@ -4094,7 +4094,15 @@ Clicks that are not over any visible ZScreen element, of course, are passed
 through to the underlying viewscreen.
 
 If :kbd:`Esc` or the right mouse button is pressed, and the ZScreen widgets
-don't otherwise handle them, then the top ZScreen is dismissed.
+don't otherwise handle them, then the top ZScreen is dismissed. If the ZScreen
+is "locked", then the screen is not dismissed and the input is passed on to the
+underlying DF viewscreen. :kbd:`Alt`:kbd:`L` toggles the locked status if the
+ZScreen widgets don't otherwise handle that key sequence. If you have a
+``Panel`` with the ``lockable`` attribute set and a frame that has pens defined
+for the lock icon (like ``Window`` widgets have by default), then a lock icon
+will appear in the upper right corner of the frame. Clicking on this icon will
+toggle the ZScreen ``locked`` status just as if :kbd:`Alt`:kbd:`L` had been
+pressed.
 
 Keyboard input goes to the top ZScreen, as usual. If the subviews of the top
 ZScreen don't handle the input (i.e. they all return something falsey), the
@@ -4122,14 +4130,16 @@ ZScreen provides the following functions:
   when the tool command is run and raise the existing dialog if it exists or
   show a new dialog if it doesn't. See the sample code below for an example.
 
+* ``zscreen:toggleLocked()``
+
+  Toggles whether the window closes on :kbd:`ESC` or r-click (unlocked) or not
+  (locked).
+
 * ``zscreen:isMouseOver()``
 
-  If the ZScreen subclass has a subview with a ``view_id`` equal to "main",
-  then the mouse will be considered to be over the visible viewscreen elements
-  when ``self.subviews.main:getMouseFramePos()`` returns a position. Subclasses
-  can override this function if that logic is not appropriate, for example if
-  there are multiple independent windows being shown and this function should
-  return true if the mouse is over any of them.
+  The default implementation iterates over the direct subviews of the ZScreen
+  subclass and sees if ``getMouseFramePos()`` returns a position for any of
+  them. Subclasses can override this function if that logic is not appropriate.
 
 Here is an example skeleton for a ZScreen tool dialog::
 
@@ -4159,7 +4169,7 @@ Here is an example skeleton for a ZScreen tool dialog::
     }
 
     function MyScreen:init()
-        self:addviews{MyWindow{view_id='main'}}
+        self:addviews{MyWindow{}}
     end
 
     function MyScreen:onDismiss()
@@ -4315,6 +4325,11 @@ Has attributes:
   hitting :kbd:`Esc` (while resizing with the mouse or keyboard), or by calling
   ``Panel:setKeyboardResizeEnabled(false)`` (while resizing with the keyboard).
 
+* ``lockable = bool`` (default: ``false``)
+
+  Determines whether the panel will draw a lock icon in its frame. See
+  `ZScreen class`_ for details.
+
 * ``autoarrange_subviews = bool`` (default: ``false``)
 * ``autoarrange_gap = int`` (default: ``0``)
 
@@ -4376,7 +4391,7 @@ Window class
 ------------
 
 Subclass of Panel; sets Panel attributes to useful defaults for a top-level
-framed, draggable window.
+framed, lockable, draggable window.
 
 ResizingPanel class
 -------------------
diff --git a/library/lua/gui.lua b/library/lua/gui.lua
index 4777f8186..426458159 100644
--- a/library/lua/gui.lua
+++ b/library/lua/gui.lua
@@ -706,6 +706,10 @@ function ZScreen:isOnTop()
     return dfhack.gui.getCurViewscreen(true) == self._native
 end
 
+function ZScreen:toggleLocked()
+    self.locked = not self.locked
+end
+
 function ZScreen:onInput(keys)
     if not self:isOnTop() then
         if keys._MOUSE_L_DOWN and self:isMouseOver() then
@@ -719,7 +723,13 @@ function ZScreen:onInput(keys)
     if ZScreen.super.onInput(self, keys) then
         return
     end
-    if keys.LEAVESCREEN or keys._MOUSE_R_DOWN then
+
+    if keys.CUSTOM_ALT_L then
+        self:toggleLocked()
+        return
+    end
+
+    if not self.locked and (keys.LEAVESCREEN or keys._MOUSE_R_DOWN) then
         self:dismiss()
         -- ensure underlying DF screens don't also react to the click
         df.global.enabler.mouse_rbut_down = 0
@@ -732,7 +742,6 @@ function ZScreen:onInput(keys)
     end
 end
 
--- move this viewscreen to the top of the stack (if it's not there already)
 function ZScreen:raise()
     if self:isDismissed() or self:isOnTop() then
         return self
@@ -741,10 +750,10 @@ function ZScreen:raise()
     return self
 end
 
--- subclasses should either annotate their viewable panel with view_id='main'
--- or override this and return whether the mouse is over an owned screen element
 function ZScreen:isMouseOver()
-    return self.subviews.main and self.subviews.main:getMouseFramePos() or false
+    for _,sv in ipairs(self.subviews) do
+        if sv:getMouseFramePos() then return true end
+    end
 end
 
 --------------------------
@@ -777,9 +786,11 @@ GREY_LINE_FRAME = {
     rb_frame_pen = to_pen{ tile=917, ch=188, fg=COLOR_GREY, bg=COLOR_BLACK },
     title_pen = to_pen{ fg=COLOR_BLACK, bg=COLOR_GREY },
     signature_pen = to_pen{ fg=COLOR_GREY, bg=COLOR_BLACK },
+    locked_pen = to_pen{tile=779, ch=216, fg=COLOR_GREY, bg=COLOR_GREEN},
+    unlocked_pen = to_pen{tile=782, ch=216, fg=COLOR_GREY, bg=COLOR_BLACK},
 }
 
-function paint_frame(dc,rect,style,title)
+function paint_frame(dc,rect,style,title,show_lock,locked)
     local pen = style.frame_pen
     local x1,y1,x2,y2 = dc.x1+rect.x1, dc.y1+rect.y1, dc.x1+rect.x2, dc.y1+rect.y2
     dscreen.paintTile(style.lt_frame_pen or pen, x1, y1)
@@ -802,6 +813,14 @@ function paint_frame(dc,rect,style,title)
         end
         dscreen.paintString(style.title_pen or pen, x, y1, tstr)
     end
+
+    if show_lock then
+        if locked and style.locked_pen then
+            dscreen.paintTile(style.locked_pen, x2-1, y1)
+        elseif not locked and style.unlocked_pen then
+            dscreen.paintTile(style.unlocked_pen, x2-1, y1)
+        end
+    end
 end
 
 FramedScreen = defclass(FramedScreen, Screen)
diff --git a/library/lua/gui/widgets.lua b/library/lua/gui/widgets.lua
index e95410fb2..4df6d07ff 100644
--- a/library/lua/gui/widgets.lua
+++ b/library/lua/gui/widgets.lua
@@ -81,6 +81,7 @@ Panel.ATTRS {
     resize_min = DEFAULT_NIL,
     on_resize_begin = DEFAULT_NIL,
     on_resize_end = DEFAULT_NIL,
+    lockable = false,
     autoarrange_subviews = false, -- whether to automatically lay out subviews
     autoarrange_gap = 0, -- how many blank lines to insert between widgets
 }
@@ -464,7 +465,11 @@ end
 function Panel:onRenderFrame(dc, rect)
     Panel.super.onRenderFrame(self, dc, rect)
     if not self.frame_style then return end
-    gui.paint_frame(dc, rect, self.frame_style, self.frame_title)
+    local locked = nil
+    if self.lockable then
+        locked = self.parent_view and self.parent_view.locked
+    end
+    gui.paint_frame(dc, rect, self.frame_style, self.frame_title, self.lockable, locked)
     if self.kbd_get_pos then
         local pos = self.kbd_get_pos()
         local pen = to_pen{fg=COLOR_GREEN, bg=COLOR_BLACK}
@@ -487,8 +492,20 @@ Window.ATTRS {
     frame_background = gui.CLEAR_PEN,
     frame_inset = 1,
     draggable = true,
+    lockable = true,
 }
 
+function Window:onInput(keys)
+    if keys._MOUSE_L_DOWN and self.parent_view and self.parent_view.toggleLocked then
+        local x,y = dscreen.getMousePos()
+        local frame_rect = self.frame_rect
+        if x == frame_rect.x2-1 and y == frame_rect.y1 then
+            self.parent_view:toggleLocked()
+        end
+    end
+    return Window.super.onInput(self, keys)
+end
+
 -------------------
 -- ResizingPanel --
 -------------------