the only way to add blank frames is to create one in another layer and drag it inside the filter mask, is it possible to fix this bug?
(here I added a video of the bug, also i’m on krita 5.2.3)
In the Timeline docker at the left side, it looks like you have layer ‘2’ selected so all actions take place on layer 2.
You need to click on Filter Mask 1, at the left side of the timeline, to select Filter Mask 1 so that actions happen on that layer.
People have often asked that clicking on a frame in the timeline should cause the layer of that frame to be the selected layer.
you did not understand the issue, let me rephrase that.
you cannot add BLANK frames in the filter mask, in the sense that when you CLICK on “ADD BLANK FRAME” the frame that is added is NOT BLANK.
Even you you select filter mask 1, the frames that are added when you click on “add BLANK frame” are NOT blank
I was confused by Layer 2 being selected - mea culpa.
Also, if the Mask layer is selected, then you do right-click → Create Blank Frame on a frame, you don’t get a blank frame, you get a keyframe.
I suspect this has something to do with the fact that mask layers don’t have an alpha channel and therefore can’t have ‘no content’.
Why you can then drag a blank frame from a paint layer onto a mask layer is a bit of a puzzle.
Oh damn, I see..
so, will it be possible to make the “add blank frame” work for filter masks/layers in the future?
(So basically to make it behave like paint layers when you add a blank frame on a layer that already contains a drawing)
I don’t know. That would be a question for the developers to answer.
The important question would be: What is the disadvantage to the user of not being able to create/add a blank frame directly on an animated mask layer, apart from the inconvenience of having to drag it on from a paint layer.
With that, you can make a Feature Request topic.
The disadvantages are the lack of the following advantages:
There are three advantages to having blank frames that I can think of:
- They suppress any following hold frame indicators and that gives a better and more easily understood appearance to the Timeline contents.
- I believe that a blank frame uses minimal RAM compared to a keyframe. Even if the keyframe appears to have no content, it may have lots of content that was erased by setting the alpha value of the content to zero.
- A blank frame on a mask layer is all black which may be what you want compared to a new keyframe which is all white. (see below)
A new keyframe on a mask layer, created/added by attempting to create/add a blank frame is actually all white. This has the effect of not masking out the filter effect anywhere on the frame.
A blank frame on a mask layer, placed there by dragging from an animated paint layer is all black, having the effect of masking out the filter effect.
I think this is because a blank frame of a paint layer has no stored content and therefore shows the default pixel value (usually RGB/A = 0,0,0/0).
Drag that onto a filter mask frame and it will be converted to a mask layer image by having the alpha channel removed to give a black mask image.
I may have got some of the above wrong but that would be for the developers to think about.
Edit:Add: Further experimentation with this has shown something I hadn’t noticed:
I’ve been playing with this and now have a filter mask layer that can have blank frames created/added on it. I can’t remember what I did and I can’t replicate it with another filter mask. 
If I find out what’s happening then I’ll add more information here.
Alright!
So basically I have to make a new post under “feauture request” subcategory right?
If so do I also have to write the advantages or I can put a link to this topic?
I think the Feature Request topic should be self-contained to make it easier to read.
You’re welcome to copy/paste any of my posted content above as part of the Feature Request topic you create and to add to it and edit it as you see fit.
Regarding my final Edit:Add information above, please try doing experiments with things to make sure that you can’t get a situation where it is possible to create/add a blank frame. I still don’t know what really happened there.
Masks have one bit per pixel they have no transparency like gray layers. Black colored masks already have nothing on them, ergo they are blank. Unless it is not doing that.
Masks have one channel per pixel, an 8-bit ‘value’ channel, i.e. greyscale with no alpha.
A greyscale paint layer has an 8-bit value channel and an 8-bit alpha channel.
@LoneFeline
re. My Edit:Add above:
I’ve realised that if you convert a paint layer into a filter mask then you can then create/add a blank frame to that resulting filter mask and that blank frame is black, as expected.
If you create a new filter mask then try to create/add a blank frame on it - you get a keyframe which is white.
It’s the same situation with a transparency mask.
I think this is a designed default behaviour because if you add a filter mask then you expect it to be active (all white) unless you decide to paint it black.
I don’t understand why a filter mask that was made by converting a paint layer should be able to have a blank layer created/added on it when a freshly made filter mask can’t have that.
Developer analysis and comment are needed here.
sorry. thank you for correcting it.
OMG IT WORKEDDDDD
At this point i’m wondering if it would be more convenient to keep filter masks and paint layers converted into filter masks to have a different behavior or to work the same
‘Workarounds’ are useful to know about but it would be better to get more comment on this, especially from developers.