in Delphi TIPS
:: T(Custom)Edit's AutoSelect property determines whether all the text in the edit control is automatically selected when the control gets focus. The AutoSelect property has the value of TRUE by default - when the control receives the focus, i.e. when the control is tabbed into all the text in the control will be selected.
And here's a problem!
What we want is that AutoSelect works not only when the control is tabbed into BUT also when the edit control receives the input focus as a result of a mouse click into the control...
Read the full article to learn how to How to Auto Select T(Custom)Edit Text On Mouse Click / Focus