Cannot see VB.NET window on certain computers

[RobboD]

Hi,

I need your help, please. I'll try and make this clear but to me it seems incredibly complicated.

I use UVNC to complement an app I have made. The app uses Toolbook mainly but at times it triggers a VB.Net app which displays pictures in a picturebox.

Everything worked fine on my computers. I then tested the program using Dell Optiplex 360 computers. Everything still works on the remote computer screen but on the computer using VNCViewer (whether it's mine or a Dell) the Toolbook window is visible but there is not a trace of the VB.Net window.

To make things even more confusing, if I replace my complex Toolbook + VB.net program with a simple VB.Net app that just displays pictures I have no problem seeing them with VNCViewer even if the app is running on the Dells.

What could possibly make a VB.Net Window disappear when viewing the screen of a certain type of remote computer ???

I would greatly appreciate any enlightenment.

[redge]

is the vb.net use hardware accelerator of video display adapter ? is the most case of nothing at vncviewer
need to disable mirror video driver on computer where is installed ultravnc server but this slowdown.

[RobboD]

Hi,

Many thanks for your quick reply. Unfortunately, I still haven't solved the problem.

I am not using the UVNC mirror driver so I think your first suggestion about disabling the video driver accelerator must be the answer because that would explain why this problem only exists on certain computers and not others.

I think the installed driver is Intel(R) GMA Driver (G31/G32 Express Chipset). I have completely disabled this on one computer but this has not solved the problem. I have tried disabling all acelerations but this doesn't work either.

Do you have any other ideas please?

[RobboD]

Hello again,

I have solved the problem by modifying my VB.NET application. In case anyone else runs into this problem, here is the explanation:

On certain types of computer (Dell Optiplex 360 for example), VB.NET forms that use a TransparencyKey color are invisible in UltraVNC VNCViewer used on a remote computer. Also, simply changing the color of the form's BackColor will not solve the problem. The form's TransparencyKey property must be returned to Nothing by using "reset" in the form's property list. This means the transparent function cannot be used.

No amount of tinkering with the computer's graphics acceleration made any difference although, of course, it may well be possible to solve the problem this way.

Thanks again for your help

[Robert_Zenz]

Another possible solution:

Code: Select all

UltraVNCServer -> Admin Properties -> [Check] Capture Alpha-Blending

[RobboD]

Hello Robert,

Thank you for your helpful suggestion. You are absolutely right. Do you think 'Capture Alpha-Blending' will always work whatever type of computer is used?

I spent the whole day yesterday modifying my programme so that it works without using transparency. I'm not sure whether to undo all the modifications or not.

[Robert_Zenz]

I think this will work for every computer, yes.

If you need or want those Transparency effects, then yes, readd it and try again. Also hit 'Apply' first before closing the dialog.

[RobboD]

Hi Robert,

Two more things, please:

- I can't see an 'Apply' button. Maybe I'm not using the latest version of Ultra VNC?

- I have another (less serious) dysfunction. When I link to a remote computer to watch its screen, the cursor on the remote screen trembles all the time as long as the two computers are linked. I mean the cursor on the remote computer's screen, not the copy of that screen in VNCViewer. I have determined that this is a side effect of 'Capture Alpha-Blending' and occurs on all the types of computer I have.

Is this inevitable?

I'm writing a programme that, amongst other things, allows teachers to monitor students' computer screens. A trembling cursor signalling that teacher is watching is not ideal!

Many thanks for your time.

[Robert_Zenz]

The Apply button should have been there for quiet some time: http://www.uvnc.com/install/configuration.html

Also, I don't know about a problem with a jumping/trembling cursor. If you're not using the latest version, please update to 1.0.8.2. If the problem still exists with that version, please report it in the appropriate sub-forum. I'm sure a team member will be able to track it down.