Issues with some vb6 datagrids on Windows 7

Question

I apologize in advance for the long question...

I have a really large project written in VB6 that I need to use on some Windows 7 PCs. There are many forms with datagrids on them. Three of these datagrids are buggy in the sense that they (a) have remnants of what was on the screen before the datagrids are shown (portions of the desktop, or other parts of the application underneath the datagrid) and (b) clicking, highlighting, and scrolling doesn't work properly (selection of one row doesn't de-select another row, scrolling one way doesn't let you scroll back, among other bugginess).

Additional Info:

• on WindowsXP and Win7 32-bit, the problem does not appear; it only appears on Win7 64-bit
• If vb6 is installed (yes, with the numerous errors along the way) on the Win7 64-bit machine, the problem disappears
• There are some issues with one other grid's rows being blacked out and many of the textboxes in the app being very dark and hard to read (on both Win7 32 and 64-bit), but this is corrected in both cases by switching to the Windows 7 classic theme (aero off)

What I have tried:

• Manipulated the MsDatGrd.ocx many times. I copied it from the working WinXP, from the Win7 32-bit, and even from the original vb6 SP6 installation disk. I tried each replacement of the ocx file in the syswow64 and system32 folders, unregistering and re-registering in each place. I should note that when I unregistered the file (regsvr32.exe from both the system32 and syswow64 folders) and received the success notice, I still found it in the registry (regedit).
• I tried creating a new form and copied the controls and code over to the new form.
• I tried removing the reference to the ocx at the top of the form in Notepad (where it says Object = "{CDE57A40-8B86-11D0-B3C6-00A0C90AEA82}#1.0#0"; "MSDatGrd.ocx"). I didn't even get an error in this case, but the grid still worked as expected. The only time I was able to get any response from manipulating the ocx file was when I deleted it from syswow64; at that point, the app just wouldn't open.

The reason I thought the form itself might be an issue was because I came across log files from the two forms with the broken datagrids (note: 1 datagrid on each form). I guess the log files were generated a while back during one compilation. They both say the following:

Could not create reference: '{CDE57A40-8B86-11D0-B3C6-00A0C90AEA82}#1.0#0'.
Could not create reference: '{831FDD16-0C5C-11D2-A9FC-0000F8754DA1}#2.1#0'.

Note: the first reference in each file is the msdatgrd.ocx, the 2nd is the mscomctl.ocx (which doesn't seem to have any problem).

So...is there anything else anyone can think of to help me solve this issue? I would prefer to fix the problem instead of using another method like using the mshflexgrid or a 3rd party grid, etc.

Answer 1

You may find you get rid of a lot of issues by running the exe in compatibility mode. Right click the exe file. Then select properties, then the compatibility tab. Tick the box that says 'run this program in compatibility mode for :' and select 'Windows XP (service pack 3)'

Click apply and save etc and then try running your application again.

The problem with the blacked out rows will be that the colour was changed from the default in design and a colour was chosen from the system palette rather than the standard palette, as in highlight, highlight text etc. If you were then to change the theme on an XP machine the colours that had been set to system palette colours also change automatically to match the theme. This does not work with the Aero theme in windows 7 and the control will just appear black. I think your only option is to change the colour to a standard palette colour in the form designer or turn off aero theme (as you have already done). If you have lots of controls on lots of forms you could try a search and replace through the .frm files with the colour code using something like grepwin but I would only try this if you are confident in what you are doing, and make sure you have a backup of everything first.

The scrolling could be caused by the fact that VB6 pre-dates the mouse-wheel so you need to install a third party app to make the mouse wheel work. try 'vbscroll' or 'freewheel'. This would just effect the mouse-wheel in the IDE though as far as I know.

You could also try setting your_msflexigrid_name.redraw=true after a datagrid has been populated. This might clear up some of the display issues.

Answer 2

I'm going to post the solution I've discovered, although I wish I knew the reasoning behind it. I've found that if I place another "dummy" datagrid somewhere on the form (it can even be invisible) and bind and unbind it to the same datasource as the one bound to the buggy datagrid, the buggy datagrid works beautifully again. I noticed that when I did this, the reference to the ocx file in that form changed from lowercase to uppercase (however, when I tried just manually changing the reference from lowercase to uppercase WITHOUT adding a dummy datagrid, the issue persisted). Anyway, it is a great workaround.

Answer 3

If you have splits in your datagrid then the problem can be solved using below:

BUG: Split Causes DataGrid to Repaint Itself Continuously http://support.microsoft.com/en-us/kb/kbview/306886

Answer 4

This issue is more related to registration of DLL on window 7 64 Bit PC. On window 7 64 Bit register the datagrid under C:\Window\SYSWOW64\regsvr32.exe and everything work. Please note all the DLL of VB6 application have to register under C:\Window\SYSWOW64\regsvr32.exe YourDLLname.DLL