fix materials selection dialog

where the filter was swallowing the sublist hotkeys

docs/changelog.txt

@@ -36,6 +36,7 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 ## New Plugins
 
 ## Fixes
+- `gui/create-item`: prevent materials list filter from intercepting sublist hotkeys
 - `tiletypes`: no longer resets dig priority to the default when updating other properties of a tile
 
 ## Misc Improvements

library/lua/gui/materials.lua

@@ -56,6 +56,8 @@ function MaterialDialog:init(info)
             frame = { l = 0, r = 0, t = 4, b = 2 },
             icon_width = 2,
             on_submit = self:callback('onSubmitItem'),
+            edit_ignore_keys={'CUSTOM_SHIFT_I', 'CUSTOM_SHIFT_C',
+                              'CUSTOM_SHIFT_P'},
         },
         widgets.Label{
             text = { {