Do not handle mouse down if readonly
Do not handle mouse down if readonly

Should lead to no visible behavioural changes, is mostly an optimisation
in the current state (no selection computations, no layout
invalidation).

smoogipooo/osu-framework,ppy/osu-framework,ZLima12/osu-framework,ppy/osu-framework,ppy/osu-framework,ZLima12/osu-framework,peppy/osu-framework,smoogipooo/osu-framework,peppy/osu-framework,peppy/osu-framework