Question : "Grid Index out of range" errors at different screen resolutions

This problem only seems to occur at low screen resolutions.
A query produces a dataset which is to be displayed in a TDBGrid. The dataset is scanned to find the largest width field and this figure is used to set the column width for that field:

   dsKey->DataSet = qKey; // The TDataSource
   qKey->Open();          // a TQuery

   while(!qKey->Eof){
         Max = (Max < Canvas->TextWidth(qKey->Fields-Fields[0]->AsString)) ? Canvas->TextWidth(qKey->Fields->Fields[0]->AsString) : Max;
         qKey->Next();
         }
   dbgKey->Columns->Items[0]->Width = Max + 10;// Max is usually around 200

Ths last statement produces an EInvalidGridOperation error: "Grid index out of range", but only at lower screen resolutions. Interestingly, if this statement is repeated in a 'Catch' envelope, it is accepted.

Anyone see the flaw?

Answer : "Grid Index out of range" errors at different screen resolutions

Per recommendation, points NOT refunded and question closed.

Netminder
CS Moderator