Openbox: resize windows

gistfile1.txt

In the <keyboard> section in your ~/.config/openbox/lxqt-rc.xml file, add:

    <keybind key="A-Left">
      <action name="UnmaximizeFull"/>
      <action name="MoveResizeTo">
        <width>50%</width>
        <height>100%</height>
        <x>0%</x>
        <y>0%</y>
      </action>
    </keybind>
    <keybind key="A-Right">
      <action name="UnmaximizeFull"/>
      <action name="MoveResizeTo">
        <width>50%</width>
        <height>100%</height>
        <x>50%</x>
        <y>0%</y>
      </action>
    </keybind>
    <keybind key="A-Down">
      <action name="UnmaximizeFull"/>
      <action name="MoveResizeTo">
        <width>100%</width>
        <height>50%</height>
        <x>0%</x>
        <y>50%</y>
      </action>
    </keybind>
    <keybind key="A-Up">
      <action name="UnmaximizeFull"/>
      <action name="MoveResizeTo">
        <width>100%</width>
        <height>50%</height>
        <x>0%</x>
        <y>0%</y>
      </action>
    </keybind>

Run openbox --reconfigure to make the changes take effect.