"or use the rastport to draw something into your window."

Many thanks Thomas (again) for your help and your sample. It works great !

"I will try to send a signal or a message this evening (but without hope to much)"

Unfortunately, Signal() is processed too only when LMB is released.

I wonder how AmiDock do that when an icon is dragged over a button...

Yes Thomas, I still have a different drop zone for each icon, each adzm_ID is different when i drop a file on a icon.
The problem is that this adzm_ID is trapped by my main event loop when the LMB is released.

Yes, thank you, i tried that too but the main problem is that the program (main event loop) doesn't receive any messages/signals until LMB is released.

"Your example does not check for AMTYPE_APPWINDOWZONE messages."

I thought that you spotted that my problem of picture refresh could come from the lack of message checking

By "refresh" I meant change the button (a .info icon picture) selected state.

My problem is that I have a sort of Dock with buttons.
If I drag a workbench icon (RAM: volume icon for example) over the button of the Dock without releasing left mouse button, I would like to change the selected state of the button where my mouse is.

The hook sample that you made works great but when I use

SetGadgetAttrs((struct Gadget *)(button[adzm->adzm_ID]),window, NULL,GA_Selected, FALSE,TAG_END);

to change the selected representation of the button it crashs (as stated in the AutoDocs).

As it fails, I tried to send Signal/Messages to my main program but there are not processed until LMB is released.

Sorry if I was not enough clear before.

You are right, it's a freeze not a simple crash.

Following your advice, it's far better, no more freeze and overall the icons are selected when I drag objects over them, many thanks again :)

Now, my problem is that my background alphamap is not refreshed when an icon change from Selected to Normal, the yellow bordering halo is kept drawed.

If I use ICONDRAWA_EraseBackground, TRUE, the yellow halo is erased but my Alpha background is no more transparent...

 	struct DiskObject *iconProgramme;
 
 	iconProgramme = GetIconTags(tab_program[index],
                       ICONGETA_FailIfUnavailable, FALSE,
                       ICONGETA_UseFriendBitMap,   TRUE,
                       ICONGETA_GetPaletteMappedIcon, TRUE,
                       ICONGETA_Width,ICON_SIZE,
                       ICONGETA_Height,ICON_SIZE,                       
                       ICONGETA_ForceScaling, icon_scaling,
                       ICONGETA_AllowUpscaling, icon_scaling,
                       TAG_END ) ;
 
	GetAttrs((struct Gadget *)(button[index]),GA_Left,  &left);							
	GetAttrs((struct Gadget *)(button[index]),GA_Top,  &top);
 
	if (adzm->adzm_Action == ADZMACTION_Enter) 
	{    
 
		DrawIconState(adzm->adzm_RastPort, iconProgramme, NULL, left,top, IDS_SELECTED,
								ICONDRAWA_EraseBackground, FALSE,
								ICONDRAWA_Frameless, TRUE,
								ICONDRAWA_Borderless, TRUE,
								TAG_DONE);
	}
	else
	{
		DrawIconState(adzm->adzm_RastPort, iconProgramme, NULL, left,top , IDS_NORMAL,
								ICONDRAWA_EraseBackground, FALSE,
								ICONDRAWA_Frameless, TRUE,
								ICONDRAWA_Borderless, TRUE,
								TAG_DONE);	
 
	}
 
	if (iconProgramme)
		FreeDiskObject(iconProgramme) ;

with ICONDRAWA_EraseBackground, FALSE,

with ICONDRAWA_EraseBackground, TRUE,

Yes, my window is transparent but even when no transparent (only colored by a WA_BackFill hook or with an pattern with a WINDOW_BackFillName), the icon background is the same.

But thank you for all your advices, it's very complex for me but instructive.