OpenDialog and mouse event
lazarus / 31-LCL

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hedgehog · 2025-06-16 07:43

I noticed strange behavior of OpenDialog (Lazarus 4 and Win64)

1) Call OpenDialog.
2) Place the file selection window above the form.
3) Select the file by double-clicking

After that MouseMove event will occur for form, and Shift = [ssLeft]

Is this normal behavior?

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ASerge · 2025-06-17 16:22

Quote from: hedgehog on June 16, 2025, 09:43:17 amIs this normal
behavior?
Not confirm. Windows 7, x64, Lazarus 4.0, fpc 3.2.2. After double-
clicking on the file above the form, no mouse event occurred.

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Martin_fr · 2025-06-17 17:37

Win 10 => yes, get the mouse-move.

Not sure, if that is right or wrong.

The dialog closes on the 2nd mouse down.
I.e. you can do (on a filename in the open dlg)
- left mouse down
- left mouse up
- left mouse down (and keep down)

And the dialog will close.

Now you have
- the button down
- the dlg closed
- the mouse over the form

Since the dlg no longer exists, any mouse-capture that it might have
had, would be gone. So mouse event go - as they normally do - to the
control below the mouse.


Well, and yes, there is a mouse move. Even if the mouse did not move
since (and during) the button up/downs.
But the last mouse pos for the form was over the button, and now it is
no longer over the button. That apparently is reported as a move. (and
catching it in the debugger, it appears that it was generated by the
OS / by Windows)

If I position the form such as,
- that the file open dialog will open above it,
- and that one of the filenames will be over the area of the form
And I position the mouse cursor where that filename will be...
And then
- I lift the mouse off the table, so there will be no movement
- I trigger the dialog open via keyboard (so the mouse can be kept
were it is)
- I double click the filename (that will have appeared below the
mouse)
  and optionally keep the button down on the 2nd click...
=> then there is no move being reported.

But of course, if I keep the button down, and start moving the mouse,
then there will be.

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hedgehog · 2025-06-19 06:06

I forgot to say that I have Windows 10.
My application uses mouse control.
And when using OpenDialog I noticed some incorrect behavior.

I think OpenDialog should not pass mouse events

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jcmontherock · 2025-06-19 09:37

It's work fine in Windows 11