TSysControl.GetText will truncate text to 1K characters

[jpluimers]

TSysControl.GetText will truncate text to 1K characters. This is less worse than the VCL which - up to 10.1 Berlin - did this:

function GetSysWindowText(Window: HWND): string;
var
  Text: array[0..256] of Char;
begin
  SetString(Result, Text, Winapi.Windows.GetWindowText(Window, Text, Length(Text)));
end;

A solution like below is more flexible:

function GetSysWindowText_WMGetText(Window: HWND): string;
var
  RequiredTextLength: Integer;
  ObtainedTextLength: Integer;
begin
  RequiredTextLength := SendMessage(Window, WM_GETTEXTLENGTH, 0, 0);
  SetString(Result, PChar(nil), RequiredTextLength);
  if RequiredTextLength <> 0 then
  begin
    ObtainedTextLength := SendMessage(Window, WM_GETTEXT, WParam(RequiredTextLength + 1), LParam(PChar(Result)));
    if ObtainedTextLength < RequiredTextLength then
      SetLength(Result, ObtainedTextLength);
  end;
end;

Two notes:

• Getting the text can be done by using GetWindowText or by sending a WM_GETTEXT message; The secret life of GetWindowText – The Old New Thing. TL;DR: explains the difference and favours WM_GETTEXT, and in-process GetWindowText will use WM_GETTEXT.
• In the use-case I needed the fix for, the VCL DrawToolTipText in the Vcl.SysStyles unit cannot word-wrap long TTS_ALWAYSTIP based hint texts, but now at least they are longer