GTS (MMP) series modules mouse over issue

Using 3.4.2 and any of the GTS series games get the messages about using custom JAVA code that will not work after Aug2021 and more importantly when using the Mouse Hover feature the images of the units apear about 5-6 hexes away, to the upper left, of the stack. See attached image.


Thanks very much for the report. I am guessing you are on a Mac with a Retina display, or have changed the window scaling on a Mac or Linux system?

We are in the process of releasing new versions of all GTS modules that will be fully compatible with Vassal 3.4 and will also fix these (and other) scaling issues on HiDPI displays, as well as a raft of other bugs. We hope to have the updated versions out within the week.


No standard Win 10 machine. I do have a very high res monitor however. The modules, GTS series, are the only ones with this issue. No issues with 3.2.17.

Ok, thanks for the info. HiRes monitors are a problem on all system First cab of the rank in Gold, Juno & Sword which is being uploaded now. You should see it within the next day.

Please test and let us know the results.


I have got the new version 1.9.2 of Gold, Juno & Sword uploaded now, could you try it out please?


I’ll note from the screenshot, the original poster was dealing with the Operation Mercury module (the same one that got me searching on GTS here.

I’m not having the mouse-over issue he reports, so I can’t say anything about that.

However, TGD v1.9.2 does indeed fix the custom code warning.

Also, as soon as I move a unit in the Op Mercury module, I get the following error pop up:

This module contains custom code that is calling into VASSAL in a way that is no longer recommended (Custom trait calling setProperty(Properties.SNAPSHOT, PieceCloner.getInstance().clonePiece(p))). This may result in poor performance and/or bugs.

Please check whether there is an updated version of this module. If not, please contact the maintainer of this module and request that it be fixed, or post a message on the Vassal forums and ask for help.

However, this doesn’t happen in the TGD module, so that is probably fixed in that version.

Hello RIndis,
I am helping Brent maintain the GTS modules. I have an unpublished version of Crete that you can try out if you want. Send me an email and I will send you a link to the module. It contains most of the latest custom code fixes that are available in TGD.


It hit me this morning that I do have access to a high-DPI screen; my Surface Pro 6.

So, I checked Operation Mercury on it, and indeed the hoverovers appear some distance away from the counters (took a bit to confirm, as they were generally going off-screen). I then checked the current version of TGD, and that did work as expected, so I’d say the general module fixes are ready to go.

And another, separate note for the Operation Mercury module when it gets updated:

The 12./III./FJR 2 unit is missing from the first scenario setup (the printed book lists four units, and then says there’s three for Stick 2, the PDF says 4 units, so that would be the source of that little problem).

So I upgraded my laptop a while back. I was in the middle of a PBEM game of TDC. When I downloaded the newest vassal version and the TDC mod I immediately had many issues with errors and mouseover problems.

Reading this thread I was able to figure out that having Vassal version 3.2.17 and the newest TDC modifier fixes all the issues. The problem now is that I can’t load other Mods like TGD cause the Vassal version is to old.

Is there anyone working on updating the GTS mods to work with the newer Vassal versions? Could I have 2 different versions of Vassal installed at the same time? Either way to those who help update and maintain these mods, Thank you!

You CAN have multiple versions of VASSAL installed at the same time. Just grab the latest version from the site, and when you start the installer select “Custom Installation”. That will allow you to keep any existing versions that you want.

I’ll let Brent, Claudio, etc, speak to the specific GTS mods.


Fireguy, or anyone interested in the latest GTS module version,
send me a mail at I will give you a link to download the latest version of the module.
You will need the latest Vassal version (3.5.5 or later) to play it. As Brian said, you can keep 3.2.17 on the same PC where you install 3.5.5