Fix from John Ehresman where page mode caching with small window caused 0 length cache.
Fix from John Ehresman where page mode caching with small window caused
0 length cache.

keperlia/foo-wsh-panel-mod.scintilla,keperlia/foo-wsh-panel-mod.scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla