This question focuses on Lubuntu, which comes with
openbox included in its latest version (14.04.5). As pointed out in the comments, by configuring the
~/.config/openbox/lubuntu-rc.xml file, you can affect the applications included in the
~/.config/autostart, that are run on startup. The following lines added to the
<applications> section will place the
lxterminal window on the left half, and the
gedit window on the right half.
<!-- Allocate 'lxterminal' in the left half-->
<!-- Allocate 'gedit' in the right half-->
To learn more follow this link.
Update: Regarding how to make it fit to exactly 50% of the screen, it's been posted in the comments (edited):
lxterminal, like some other terminals, uses characters (in width) and rows for height!
keybind section), you can
sh -c "wmctrl -xa LXTerminal || lxterminal --geometry=84x44 2>/dev/null"
Then, in the applications section, you write:
<application class="Lxterminal" name="lxterminal">
But you have to get the values for
lxterminal by trial and error for the screen with the particular chosen font type and font size.