Have you tried simply
panel_editor.size_x += healthgained;
panel_editor.size_x -= healthlost;
If that doesnt help, try putting a wait(1); in after any size change.
If even THAT doesnt help, try (both lines together))
reset(panel_editor,SHOW);
set(panel_editor,SHOW);
Never mind i got it, your suggestion worked, thanks a lot dude.