[Lazarus] intercepting keyboard events

[Ondrej Pokorny]

On 22.05.2017 15:57, Graeme Geldenhuys via Lazarus wrote:
> On 2017-05-08 17:46, zeljko via Lazarus wrote:
>> Just to be sure that control actually can take focus put this
>> ControlStyle := ControlStyle - [csNoFocus];
>> into constructor of your control.
>
> And what if that doesn't work? I've set that in the constructor, but 
> still it doesn't receive keyboard focus (after I've clicked on the 
> custom control)?
>
> What else can I try?
>
> eg:
>   I have a PageControl which contains my custom control. I then have a 
> treeview on the right. If the treeview had focus, and I click on my 
> custom control and then press some keys (eg: Up/Down) then the focused 
> node in the treeview changes. Keyboard focus doesn't seem to want to 
> move to the custom control.
>
> ps #2:
>   Interacting with a mouse on my custom control seems to work (but 
> then I have SetFocus in the MouseDown too).

Zeljko was wrong in his statement. The csNoFocus is just a helper flag 
that custom controls should follow but don't have to. TWinControl 
directly doesn't do anything. with csNoFocus - it doesn't have any 
meaning for it.

Follow my instruction from my previous email in this thread:

If you mean receiving focus by clicking on it then yes, you need to call 
SetFocus in MouseDown. It's also a good idea to check the csNoFocus flag 
(from ControlStyle property).

For an example look how it is done in TCustomDBGrid.MouseDown.

+ The control can always get focused by the Tab key, if TabStop=True.

Ondrej