diff --git a/coordinator/startup.lua b/coordinator/startup.lua
index 9294633..a3cf6fa 100644
--- a/coordinator/startup.lua
+++ b/coordinator/startup.lua
@@ -22,7 +22,7 @@ local sounder     = require("coordinator.sounder")
 
 local apisessions = require("coordinator.session.apisessions")
 
-local COORDINATOR_VERSION = "v0.21.1"
+local COORDINATOR_VERSION = "v0.21.2"
 
 local println = util.println
 local println_ts = util.println_ts
diff --git a/coordinator/ui/pgi.lua b/coordinator/ui/pgi.lua
index 5e4077f..b603465 100644
--- a/coordinator/ui/pgi.lua
+++ b/coordinator/ui/pgi.lua
@@ -52,6 +52,8 @@ function pgi.delete_pkt_entry(session_id)
         if not success then
             log.error(util.c("PGI: failed to delete PKT entry (", result, ")"), true)
         end
+    else
+        log.debug(util.c("PGI: tried to delete unknown PKT entry ", session_id))
     end
 end
 
diff --git a/graphics/core.lua b/graphics/core.lua
index cff4ff5..534d4e2 100644
--- a/graphics/core.lua
+++ b/graphics/core.lua
@@ -7,7 +7,7 @@ local flasher = require("graphics.flasher")
 
 local core = {}
 
-core.version = "1.0.1"
+core.version = "1.0.2"
 
 core.flasher = flasher
 core.events = events
diff --git a/graphics/element.lua b/graphics/element.lua
index 4630a53..145ee0c 100644
--- a/graphics/element.lua
+++ b/graphics/element.lua
@@ -71,7 +71,8 @@ function element.new(args, child_offset_x, child_offset_y)
         p_window = nil,                                 ---@type table
         position = { x = 1, y = 1 },                    ---@type coordinate_2d
         bounds = { x1 = 1, y1 = 1, x2 = 1, y2 = 1 },    ---@class element_bounds
-        next_y = 1,
+        next_y = 1,                                     -- next child y coordinate
+        next_id = 0,                                    -- next child ID
         subscriptions = {},
         mt = {}
     }
@@ -352,13 +353,14 @@ function element.new(args, child_offset_x, child_offset_y)
 
         local child_element = child.get()
 
-        if key == nil then
-            table.insert(protected.children, child_element)
-            return #protected.children
-        else
-            protected.children[key] = child_element
-            return key
+        local id = key  ---@type string|integer|nil
+        if id == nil then
+            id = self.next_id
+            self.next_id = self.next_id + 1
         end
+
+        protected.children[id] = child_element
+        return id
     end
 
     -- remove a child element
diff --git a/supervisor/panel/pgi.lua b/supervisor/panel/pgi.lua
index 9065f72..dd8b202 100644
--- a/supervisor/panel/pgi.lua
+++ b/supervisor/panel/pgi.lua
@@ -60,6 +60,8 @@ function pgi.delete_rtu_entry(session_id)
         if not success then
             log.error(util.c("PGI: failed to delete RTU entry (", result, ")"), true)
         end
+    else
+        log.debug(util.c("PGI: tried to delete unknown RTU entry ", session_id))
     end
 end
 
@@ -87,6 +89,8 @@ function pgi.delete_pdg_entry(session_id)
         if not success then
             log.error(util.c("PGI: failed to delete PDG entry (", result, ")"), true)
         end
+    else
+        log.debug(util.c("PGI: tried to delete unknown PDG entry ", session_id))
     end
 end
 
diff --git a/supervisor/startup.lua b/supervisor/startup.lua
index 123ba21..59f5c4f 100644
--- a/supervisor/startup.lua
+++ b/supervisor/startup.lua
@@ -21,7 +21,7 @@ local supervisor = require("supervisor.supervisor")
 
 local svsessions = require("supervisor.session.svsessions")
 
-local SUPERVISOR_VERSION = "v0.20.3"
+local SUPERVISOR_VERSION = "v0.20.4"
 
 local println = util.println
 local println_ts = util.println_ts