Issue With Eraser Tool / Alpha

Hi there. Today I updated a new patch for Pro Motion through Steam, and since it has been downloaded I seem to have a couple of issues related to the eraser tool and alpha transparency that I didn’t previously have. So, because I am not sure of whether the way the alpha transparency system works has changed, or it is a bug I figured I would describe it here in the hope of sorting it as quickly as possible.

So… when I start a new file with alpha transparency, I am having an issue where the secondary paint brush (mouse right click) can’t be made into an eraser. The primary (left click) can. When I make the primary colour transparent, then try to switch the foreground and background colours, it always switches the secondary to white.

As I was unsure if I might have accidentally done something to one of the settings, I reset the program settings to default. Then closed the program and opened it. I also turned the pc on and off again. The problem remained. Any non-alpha files are working fine, it’s just any file that starts with alpha transparency that is having a problem.

I should say, I have been using this program for well over a year and one of the regular bugs that pops up is that exact issue happening to alpha and non-alpha files. But normally when it won’t allow me to use the right click as an eraser/transparency, I just turn Pro Motion on and off and it’s fine.

Thanks for any assistance.


So, I realised just now that right clicking the transparency button next to the colours still allows the secondary colour to become transparent, which made me feel a bit silly. I guess the issue is actually with the flip colour button. Pressing that switches both colours to white in an alpha file, but other project types are fine.

Edit Again

I seem to be having problems getting the secondary paint brush to work consistently. I had forgotten that one of the initial problems that had happened when the transparency/eraser was misbehaving was that drawing on the canvas while having the normal paint brush equipped was causing nothing to happen. I had to change colours several times, and it started to work again.

Hi @BearSayPlease,

I must admit that I did not 100% understand the problems, but I think we can nail them down.
First of all:
Pro Motion’s Alpha transparency is not the same as with true color drawing because it uses color palettes. When you use any true color painting program such as Gimp then the pixel color of a transparent pixel is always full white.
Since PM can only use colors that are in the color palette it by default tries to use the color index that has white for all pixels that have zero alpha and thus are fully transparent. You can change this in either the settings of a single layer (only recommended if this is really required for some reason) or here:

The best approach (to me) is to have a fixed white color in your palette that you never change. This done by default when creating a new project.
Using full transparency (=erasing) for drawing means that the selected color (first or second) is the color slot mentioned along with 0% transparency.
You can select this by several ways:

  • hit backspace key to select it as second color
  • use pipette (hold Ctrl key) and click on a transparent pixel with either left or right mouse button
  • left- or right-click on the checker pattern icon right besides the 1st/2nd color selectors:

Having selected a “transparent color” this way you can erase with the respective mouse button in connection with any drawing tool.
But you can also erase without selecting a “transparent color” this way. You can just use the Erase paint mode from menu “Mode” or hit Ctrl + F10. Hit again to switch back. Using this paint mode you can full erase with right mouse button and soft erase with the current opacity setting when using the left mouse button.

Now, starting from this, can you explain the steps you do, what happens and what you expect to happen. Also please attach a sample project. This might also help me. Indeed there have been changes/fixes on alpha transparency and so I might have introduced a bug.
By the way, the bug you mentioned that sometimes nothing happens when you select a color and draw was one of the things I fixed (or at least tried to). If this still happens we need to pin down steps that make me understand the circumstances.