From 8a710798f7f01924b9d0cd76ee4b54cce2955984 Mon Sep 17 00:00:00 2001
From: Bill Ferguson <wpferguson@gmail.com>
Date: Sun, 9 Aug 2020 00:17:34 -0400
Subject: [PATCH] Added check to ensure we are in lighttable view prior to
 callling darktable.register_lib.  If darktable was invoked in single image
 (darkroom) mode, then an event handler is registered to detect the change
 from darkroom mode to lighttable mode so that we can then call
 darktable.register_lib.

---
 contrib/ext_editor.lua | 58 ++++++++++++++++++++++++++++++++----------
 1 file changed, 44 insertions(+), 14 deletions(-)

diff --git a/contrib/ext_editor.lua b/contrib/ext_editor.lua
index 4035c22..6999c05 100644
--- a/contrib/ext_editor.lua
+++ b/contrib/ext_editor.lua
@@ -84,6 +84,12 @@ du.check_min_api_version("5.0.2", MODULE_NAME)  -- darktable 3.x
 -- OS compatibility
 local PS = dt.configuration.running_os == "windows" and  "\\"  or  "/"
 
+-- namespace
+local ee = {}
+ee.module_installed = false
+ee.event_registered = false
+ee.widgets = {}
+
 
 -- translation
 local gettext = dt.gettext
@@ -329,6 +335,26 @@ local function export2collection(storage, image_table, extra_data)
   dt.print (_("finished exporting"))
   end
 
+-- install the module in the UI
+local function install_module()
+  if not ee.module_installed then
+    -- register new module "external editors" in lighttable ------------------------
+    dt.register_lib(
+      MODULE_NAME,          
+      _("external editors"),  
+      true, -- expandable
+      false,  -- resetable
+      {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},  
+      dt.new_widget("box") {
+        orientation = "vertical",
+        table.unpack(ee.widgets),
+        },
+      nil,  -- view_enter
+      nil   -- view_leave
+      )
+    ee.module_installed = true
+  end
+end
 
 -- combobox, with variable number of entries ----------------------------------
 local combobox = dt.new_widget("combobox") {
@@ -381,22 +407,26 @@ local box1 = dt.new_widget("box") {
   button_update_list
   }
 
+table.insert(ee.widgets, combobox)
+table.insert(ee.widgets, box1)
 
 -- register new module "external editors" in lighttable ------------------------
-dt.register_lib(
-  MODULE_NAME,          
-  _("external editors"),  
-  true, -- expandable
-  false,  -- resetable
-  {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},  
-  dt.new_widget("box") {
-    orientation = "vertical",
-    combobox,
-    box1
-    },
-  nil,  -- view_enter
-  nil   -- view_leave
-  )
+if dt.gui.current_view().name == "lighttable" then
+  install_module()
+else
+  if not ee.event_registered then
+    dt.register_event(
+      "view-changed",
+      function(event, old_view, new_view)
+        if new_view.name == "lighttable" and old_view.name == "darkroom" then
+          install_module()
+         end
+      end
+    )
+    ee.event_registered = true
+  end
+end
+
 
 
 -- initialize list of programs and widgets ------------------------------------