The problem I have is, for example, when using undo (u in normal mode) or redo, sometimes the message, like
1 change; before #520 09:20:15
stays, but more often it flickers for a split second and is then erased. Then I have to go to :mess to read it.
The reason seems to be that the message is erased whenever the window is redrawn. (Because in cases when the line above isn't erased, if I resize the gVim window, it causes a redraw and the message disappears at that point.)
I think it would be better if the latest message were displayed until something else starts happening in the message/command line, as opposed to on redraw. But I can't find any pointers to help change that behaviour.
redraw!ing, I don't think this is normal. Do you use any plugins which might be doing this?$VIM/plugin,$VIM/autoload,vimfiles/plugin,vimfiles/autoloaddirectories temporarily to a different place, restarted gVim, and it's still happening. Hard to say what is causing the redraws, but it's a common event: even scrolling using the scrollbar or the mouse wheel causes a redraw.lazyredrawoption, but I doubt this will work. Once you resize the Vim window, it must be redrawn.