Application freeze with ComboBoxes

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Hello everybody,

I've found a weird bug with the CodeJock ComboBoxes which freezes the whole application.

I'm using the ActiveX version with VB6.

You can reproduce the problem with these steps:
Create a new application and add the necessary CodeJock references
Add two ComboBoxes to the form and set their appearance to Office 2007 (helps later)
Add a ProgressBar and set Scrolling to Marquee (helps later)
Add a PushButton or a standard CommandButton to the form
Assign a mnemonic to the caption, so you can trigger the button using, let's say, Alt+O
Add a MsgBox call to the Click handler of the button
Run the application
Now focus the first ComboBox by clicking on it and move the mouse cursor on top of the second one
If you did everything right, both ComboBoxes should be highlighted (only visible with Office2007 appearence) and the ProgressBar should be scrolling
Now take your hand away from the mouse (Very important)
Press Alt+O so the message box appears
Still, don't move the mouse!
Now the application is frozen: The ProgressBar has stopped and the messagebox cannot be closed via keyboard. Also no painting happens (Not noticable with this small demo, but try Alt-Tabbing back and forth, there's no repaint. Even the VB6 IDE is frozen)
To get the application going again, you have to move the mouse cursor away from the second ComboBox
As soon as it leaves the bounds of the combobox everything works again

Here are some other facts I gathered:
The problem exists in CodeJock 13.0 and 13.1
It exists on at least four different workstations (WinXP and Vista)
The control appearence doesn't affect this
The problem exists when starting from the IDE and from the compiled .exe file
The problem does not occour when the combobox has the list style, i.e. it has to be editable to product this bug

I've spent 6 full hours to finally figure this out, and most likely my boss
will not be very happy with that. 
Please help me, so I can tell him, it wasn't for nothing :) 

Perhaps this can be circumvented or - even better - there's already a fix for it.

Thank you in advance,
Daniel

EDIT: It's not necessary to have two comboboxes. It's sufficient, if the mouse hovers over a combobox, regardless of any other controls in the form.

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daniel_r Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 06 October 2009 Location: Germany Status: Offline Points: 14	Post Options Post Reply Quote daniel_r Report Post Thanks(0) Quote Reply Topic: Application freeze with ComboBoxes Posted: 06 October 2009 at 10:42am
	Hello everybody, I've found a weird bug with the CodeJock ComboBoxes which freezes the whole application. I'm using the ActiveX version with VB6. You can reproduce the problem with these steps: Create a new application and add the necessary CodeJock references Add two ComboBoxes to the form and set their appearance to Office 2007 (helps later) Add a ProgressBar and set Scrolling to Marquee (helps later) Add a PushButton or a standard CommandButton to the form Assign a mnemonic to the caption, so you can trigger the button using, let's say, Alt+O Add a MsgBox call to the Click handler of the button Run the application Now focus the first ComboBox by clicking on it and move the mouse cursor on top of the second one If you did everything right, both ComboBoxes should be highlighted (only visible with Office2007 appearence) and the ProgressBar should be scrolling Now take your hand away from the mouse (Very important) Press Alt+O so the message box appears Still, don't move the mouse! Now the application is frozen: The ProgressBar has stopped and the messagebox cannot be closed via keyboard. Also no painting happens (Not noticable with this small demo, but try Alt-Tabbing back and forth, there's no repaint. Even the VB6 IDE is frozen) To get the application going again, you have to move the mouse cursor away from the second ComboBox As soon as it leaves the bounds of the combobox everything works again Here are some other facts I gathered: The problem exists in CodeJock 13.0 and 13.1 It exists on at least four different workstations (WinXP and Vista) The control appearence doesn't affect this The problem exists when starting from the IDE and from the compiled .exe file The problem does not occour when the combobox has the list style, i.e. it has to be editable to product this bug I've spent 6 full hours to finally figure this out, and most likely my boss will not be very happy with that. Please help me, so I can tell him, it wasn't for nothing :) Perhaps this can be circumvented or - even better - there's already a fix for it. Thank you in advance, Daniel EDIT: It's not necessary to have two comboboxes. It's sufficient, if the mouse hovers over a combobox, regardless of any other controls in the form.