comboBOX input 非常,then in "DropDown" event write
var
ist:integer;
begin
ist:=ComboBox1.SelStart;
if ist>2 then
Beep;
end;
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Tedit Tmemo return 2,but TcomboBox return 4
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FPC version 3.2.2 Lazarus verison 2.26 stable ,win11 x64