Added custom event on_visibility_changed_by_click

Fixed warp flow issue because of this

expcore/gui/left_flow.lua

@@ -52,7 +52,7 @@ end)
 
 ]]
 function Gui.left_toolbar_button(sprite,tooltip,element_define,authenticator)
-    return Gui.element{
+    local button = Gui.element{
         type = 'sprite-button',
         sprite = sprite,
         tooltip = tooltip,
@@ -62,9 +62,26 @@ function Gui.left_toolbar_button(sprite,tooltip,element_define,authenticator)
         padding = -2
     }
     :add_to_top_flow(authenticator)
-    :on_click(function(player,_,_)
-        Gui.toggle_left_element(player, element_define)
+
+    -- Add on_click handler to handle click events comming from the player
+    button:on_click(function(player,_,_)
+        local top_flow = Gui.get_top_flow(player)
+        local element = top_flow[button.name]
+        local visibility_state  = Gui.toggle_left_element(player, element_define)
+
+        -- Raise custom event that tells listening elements if the element has changed visibility by a player clicking
+        -- Used in warp gui to handle the keep open logic
+        button:raise_custom_event{
+            name = Gui.events.on_visibility_changed_by_click,
+            element = element,
+            state = visibility_state
+        }
     end)
+
+    -- Add property to the left flow element with the name of the button
+    -- This is for the ability to reverse lookup the button from the left flow element
+    element_define.toolbar_button = button.name
+    return button
 end
 
 --[[-- Draw all the left elements onto the left flow, internal use only
@@ -137,6 +154,34 @@ function Gui.hide_left_flow(player)
     hide_button.visible = false
     for name,_ in pairs(Gui.left_elements) do
         left_flow[name].visible = false
+
+        -- Get the assosiated element define
+        local element_define = Gui.defines[name]
+        local top_flow = Gui.get_top_flow(player)
+
+        -- Check if the the element has a button attached
+        if not element_define.toolbar_button then
+            goto hide_left_flow_end
+        end
+
+        -- Check if the topflow contains the button
+        local button = top_flow[element_define.toolbar_button]
+        if not button then
+            goto hide_left_flow_end
+        end
+
+        -- Get the button define from the reverse lookup on the element
+        local button_define = Gui.defines[element_define.toolbar_button]
+
+        -- Raise the custom event if all of the top checks have passed
+        button_define:raise_custom_event{
+            name = Gui.events.on_visibility_changed_by_click,
+            element = button,
+            state = false
+        }
+
+        -- Label for the end of the loop
+        ::hide_left_flow_end::
     end
 end
 

expcore/gui/prototype.lua

@@ -350,5 +350,12 @@ Gui._prototype_element.on_text_changed = event_handler_factory(defines.events.on
 -- @tparam function handler the event handler which will be called
 Gui._prototype_element.on_value_changed = event_handler_factory(defines.events.on_gui_value_changed)
 
+--- Element Events.
+-- @section customEvents
+Gui.events = {
+    -- Triggered when a user changed the visibility of a left flow element by clicking a button
+    on_visibility_changed_by_click = 'on_visibility_changed_by_click'
+}
+
 -- Module return
 return Gui