Am I restricted to the cursor numbers defined in Controls.pas under Delphi 7?

Question

I am using Delphi 7 under Windows 7 to download files.

I want to change the cursor during the download.

I set the Screen.Cursor := crHourG

Answer 1

The "standard numbers" (crHourglass, crDefault, etc) are the predefined cursors that are provided by Delphi's VCL. You can define your own and load them into the application from a resource or from file via the Windows API, but there are no magic unpublished TCursor definitions (or stray numbers) that will mean anything. Trying to set Screen.Cursors[] to an unknown number without first loading a cursor will cause an array out of bounds error at minimum, and an access violation at the worst result in the default cursor being displayed (see TScreen.GetCursors in Forms.pas).

Quick explanation: TCursorRec is defined in the VCL source as a record containing a pointer to the next record, an index, and a cursor handle (HCURSOR). It's basically a singly-linked list, and when you ask for a cursor by accessing the Cursors list, the VCL looks through the list starting at the first item and sequentially stepping through until it either finds an index that matches the one you requested (at which point it sets the cursor to that item's HCURSOR value), or determines that the index you requested isn't assigned, in which case it returns the default cursor.