ListBox: ActiveGadget()=NULL

Archives Forums/MaxGUI Bug Reports/ListBox: ActiveGadget()=NULL

Midimaster

(Posted 2013) [#1]

This report points to a difference between MaxGui for Windows and MaxGui for OsX. On OsX it causes a crash:

The function ActiveGadget() should retun the active Gadget. When I click on an item in a listbox, tihs function return the listbox itself.

On OsX the function return NULL.

To simulate the bug use the original manual example for CreateListBox() and add this lines:

.....
While WaitEvent()
	Print CurrentEvent.ToString()
	Select EventID()
		.....
	End Select
;add this:------------------------------------------------------------
	Print "step 1"
	Print "WINDOW GADGET=" + GadgetText(Window)
	If ActiveGadget()<>Null
		Print "Gadget is aktiv"
	Else
	    Print "Gadget is NULL"
	EndIf
	Print "step 2"
	Print "Name of Gadget=" + GadgetText(ActiveGadget())
;--------------------------------------------
Wend

I know it is not good to call GadgetText() of a NULL object, but remember on Windows the ActiveGadget() returns a value!!!

This bug is fatal if you want to know, in which window an event occured. Normaly you can search for the mother of a gadget upto you reach a "WINDOW"-Gadget:

Function SearchActiveWindow:TGadget()
	Local tmpGadget:TGadget = ActiveGadget()
	While (tmpGadget<> Null) And (GadgetClass(tmpGadget) <> GADGET_WINDOW)
		tmpGadget = GadgetGroup(tmpGadget)
	Wend
	Return tmpGadget
End Function

this is where I dedected the bug. I found the bug on OsX 10.6 with BlitzMax 1.48 (with official MaxGui)

skidracer

(Posted 2013) [#2]

Here is modified CreateListBox example. On OSX I am getting ActiveGadget and EventGadget non NULL for ListBox events, but NULL for window events like dragging the window (seems wrong) so am a bit confused.

' createlistbox.bmx

Strict

Import MaxGui.Drivers

AppTitle = "ListBox Example"

Global window:TGadget = CreateWindow( AppTitle, 100, 100, 200, 200, Null, WINDOW_TITLEBAR|WINDOW_STATUS|WINDOW_RESIZABLE )
	
	Global listbox:TGadget = CreateListBox( 0, 0, ClientWidth(window), ClientHeight(window), window )
	SetGadgetLayout listbox, EDGE_ALIGNED, EDGE_ALIGNED, EDGE_ALIGNED, EDGE_ALIGNED
	
	SetGadgetIconStrip listbox, LoadIconStrip("toolbar.png")
	
	AddGadgetItem listbox, "New", False, 0, "Create something."
	AddGadgetItem listbox, "Open", False, 1, "Open something."
	AddGadgetItem listbox, "Save", False, 2, "Save something.", "Extra Item Object!"
	AddGadgetItem listbox, "No Icon", False, -1, "This should not have an icon set."
	

SelectGadgetItem listbox, 2

While WaitEvent()
	Print CurrentEvent.ToString()
	Select EventID()
		Case EVENT_WINDOWCLOSE, EVENT_APPTERMINATE;End
		'ListBox Event(s)
		'EventData() holds the index of the corresponding listbox item.
		Case EVENT_GADGETSELECT
			SetStatusText window, "Selected Item Index: " + EventData()
		Case EVENT_GADGETACTION
			SetStatusText window, "Double-Clicked Item Index: " + EventData()
		Case EVENT_GADGETMENU
			SetStatusText window, "Right-Clicked Item Index: " + EventData()
	End Select
	
	Print "ActiveGadget="+(ActiveGadget()=Null)+" EventSource="+(EventSource()=Null)
	
Wend

Midimaster

(Posted 2013) [#3]

Hello skidracer,

this sounds strange: The problem for me is the EVENT_GADGETSELECT event. After this event the ActiveGadget() returns NULL instead of the "Listbox" on OsX 10.6

What will you tell me with your sample code? What shall I test?