[Lazarus] How can use TControl.Perfom(Perform(LM_KEYUP, VK_UP, 1);

[FreeMan]

Hello,
In my TExLookUp Component I need to sent key stroks to subcomponent 
Grid. How can I do this. Its has to be crossplatform too.
Example:
TExLookUp.EditKeyUp(........
...
   if Key=VK_UP   then FGrid.Perform(LM_KEYUP, VK_UP, 1);
   if Key=VK_DOWN then FGrid.Perform(LM_KEYDOWN, VK_DOWN, 1);
or how?
For testing, on new application, one db grid (its showing some data from 
datasource) and two button has on Tform. On buttonclick event has 
Grid.Perform(LM_KEYDOWN, VK_DOWN, 1);  and other has 
Grid.Perform(LM_KEYUP, VK_UP, 1);  but not working this codes. no any error.
my system is Kubuntu 13.10 x64 Lazarus and fpc last svn version and QT 
widgetset.
has anyone got any suggestion or idea?
Thank you