widget: Fix display glitch when starting a rectangular selection
widget: Fix display glitch when starting a rectangular selection

https://bugzilla.gnome.org/show_bug.cgi?id=730800#c10

flaxandteal/gasket-vte,jessevdk/vte,thestinger/vte-ng,flaxandteal/gasket-vte,jessevdk/vte,rvu95/vte,jessevdk/vte,flaxandteal/gasket-vte,rvu95/vte,saitoha/vte-sixel,jessevdk/vte,thestinger/vte-ng,flaxandteal/gasket-vte,rvu95/vte,saitoha/vte-sixel,thestinger/vte-ng,saitoha/vte-sixel,rvu95/vte