<packing> tags not supported by builder

[AndreiBiziuk]

I'm trying to use builder to create UI from XML files created by Glade. Glade creates <packing> tags inside various controls tags.

Example ui file:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.38.2 -->
<interface>
  <requires lib="gtk+" version="3.0"/>
  <object class="GtkWindow" id="main_window">
    <property name="can-focus">False</property>
    <property name="title" translatable="yes">Main window</property>
    <child>
      <object class="GtkBox" id="main_box">
        <property name="visible">True</property>
        <property name="can-focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkButton" id="recreate_button">
            <property name="label" translatable="yes">button1</property>
            <property name="visible">True</property>
            <property name="can-focus">True</property>
            <property name="receives-default">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkToggleButton" id="start_fit_button">
            <property name="label" translatable="yes">button2</property>
            <property name="visible">True</property>
            <property name="can-focus">True</property>
            <property name="receives-default">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <placeholder/>
        </child>
      </object>
    </child>
  </object>
</interface>

When I try to compile I get error:

failed to add UI from file main.ui: main.ui:21:1 Unhandled tag: <packing>

I have to manually remove this tags from file every time when I edit UI.

[garetxe]

Hi! Thanks for the report!

The haskell-gi autogenerated bindings do not have special support for .ui files, although it is in my list of potential future ideas. So I suspect that it is an incompatibility between gtk and glade. As a guess... are you using gi-gtk-3.* or gi-gtk-4.*? Perhaps the format of the ui files has changed between the two versions.

[AndreiBiziuk]

I am using gi-gtk-4.0 and Glade uses gtk+ 3.x so probably this is the cause of the problem. Thank you for reply!

[garetxe]

I see, that's probably the explanation then.

I personally like glade, and I think that it's a real pity that it does not support gtk4. The alternative which is often proposed is to write the .ui XML by hand, but to be honest I don't think it's worth the pain in Haskell. Here is the Haskell code that would construct the same ui (I am intentionally leaving some unnecessary things in, like #visible := True, and so on, to make the comparison easier):

mainWindow :: IO Gtk.Window
mainWindow = do
  mainBox <- new Gtk.Box [ #visible := True
                         , #canFocus := False
                         , #orientation := Gtk.OrientationVertical ]

  recreateButton <- new Gtk.Button [ #label := "button1"
                                   , #visible := True
                                   , #canFocus := True
                                   , #receivesDefault := True
                                   , #valign := Gtk.AlignFill
                                   , #vexpand := False ]
  #append mainBox recreateButton

  startFitButton <- new Gtk.ToggleButton [ #label := "button2"
                                         , #visible := True
                                         , #canFocus := True
                                         , #receivesDefault := True
                                         , #valign := Gtk.AlignFill
                                         , #vexpand := False ]
  #append mainBox startFitButton

  new Gtk.Window [ #canFocus := False
                 , #title := "Main window"
                 , #child := mainBox ]

I would argue that this is as readable as the XML (perhaps more), and the types are checked at compile time.

Anyway, I am closing since it seems like there is little that we can do on the haskell-gi side to fix this. Thanks again for the bug report!

[AndreiBiziuk]

I found very useful command that convert .ui files from gtk3 to gtk4:

gtk4-builder-tool simplify --3to4 --replace ./main.ui

[garetxe]

Thanks, that seems useful!