Swapped out the default on-screen keyboard for something lightweight.

Index: src/ipe/lua/prefs.lua
--- src/ipe/lua/prefs.lua.orig
+++ src/ipe/lua/prefs.lua
@@ -357,7 +357,7 @@ elseif config.platform == "apple" then
   prefs.keyboard = "open -a KeyboardViewer -n"
 else
   -- On Linux, you could use: prefs.keyboard = "onboard &"
-  prefs.keyboard = nil
+  prefs.keyboard = "xvkbd &"
 end
 
 -- Disable all snap modes in "ink" drawing mode?
