BBC BASIC Programmers' Reference

by Richard Russell, August 2012

As a rule, a tooltip is displayed when the mouse moves into the tool's rectangle and stays there for a specified minimum period of time; typically this is when the user 'hovers' the mouse over a control or other region of interest. However it is also possible to force a tooltip to display 'on demand', under the control of your program.

The code listing below demonstrates how to do that:

      INSTALL @lib$+"WINLIB5"

      SYS "SetWindowText", @hwnd%, "Click anywhere"

      REM!WC Windows Constants:
      CW_USEDEFAULT = &80000000
      TTM_ADDTOOL = &404
      TTM_TRACKACTIVATE = &411
      TTM_UPDATETIPTEXT = &40C
      TTS_ALWAYSTIP = 1
      TTS_BALLOON = 64
      TTS_NOPREFIX = 2
      WS_POPUP = &80000000

      hwndTT% = FN_createwindow("tooltips_class32", "", \
      \         CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, \
      \         0, WS_POPUP + TTS_NOPREFIX + TTS_ALWAYSTIP + TTS_BALLOON, 0)
      IF hwndTT% = 0 ERROR 100, "Couldn't create tooltip"

      DIM ToolInfo{cbSize%, uFlags%, hwnd%, uID%, rc{l%,t%,r%,b%}, \
      \      hinst%, lpszText%}
      ToolInfo.cbSize% = DIM(ToolInfo{})
      ToolInfo.hwnd% = @hwnd%

      ToolTipText$ = "" + CHR$0
      ToolInfo.lpszText% = !^ToolTipText$
      SYS "SendMessage", hwndTT%, TTM_ADDTOOL, 0, ToolInfo{}

      PROC_setfocus(@hwnd%)
      REPEAT
        WAIT 1
        MOUSE X%, Y%, B%
        IF B% PROCactivate
      UNTIL FALSE
      END

      DEF PROCactivate
      ToolTipText$ = "Hello tooltip!" + CHR$0
      ToolInfo.lpszText% = !^ToolTipText$
      SYS "SendMessage", hwndTT%, TTM_UPDATETIPTEXT, 0, ToolInfo{}
      SYS "SendMessage", hwndTT%, TTM_TRACKACTIVATE, 1, ToolInfo{}
      WAIT 100
      ToolTipText$ = "" + CHR$0
      ToolInfo.lpszText% = !^ToolTipText$
      SYS "SendMessage", hwndTT%, TTM_UPDATETIPTEXT, 0, ToolInfo{}
      ENDPROC

As shown, clicking anywhere will cause a balloon tooltip (available in Windows XP or later) to be displayed at the mouse position, and to remain displayed for one second. If the TTS_BALLOON style is omitted a regular tooltip will be displayed.