Here are the gestures that I use. You can see they are all straight lines.
I've tried more complex gestures but I've found not using them much over time. Currently, I only use straight-line gestures. Unfortunately, they often get detected incorrectly (different gesture triggers, nothing happens).
I'd be fine if there's a setting for a simpler and more reliable heuristic that only cares about the direction of the line. Just an angle, that's it.
<3 BetterTouchTool
I'm in the process of switching to Apple's machine learning framework for recognizing drawing gestures. As soon as this is done, straight lines will work fine 
I want to second this: as others mentioned in other threads, I'm actually using a completely different application for my gestures because, the straight-line stuff is to important.
You want to map your most frequent actions to the cheapest input.
E.g. I map the gesture "Down" to "Close Tab".
I'm not sure how much I'm adding to the conversation here, I just want to express how surprised I was with your implementation: I'm sure that it took you a while to do but, as it stands, as far most gesture junkies are concerned, it's literally as though you did not even offer the feature.
I'm greatly looking forward to the new one. 
Has there been any progress on implementing straight lines? Currently the configuration window for gestures still indicates that straight lines cannot be used.
I cannot support the request for the reliable recognition of straight-line gestures enough. I couldn't if I tried.
Mouse gestures is the one thing I use BTT for.
I've spent hours upon hours trying fine-tune the quirks of the existing engine (no matter the required recognition certainty it always prefers diagonal gestures to horizontal and vertical, it goes nuts after each reload until one opens settings, the rotation tolerance is pure madness, etc., etc.) — and still it messes up every forth or fifth gesture.
Which makes it more of a nuisance than a help.
Windows has had StrokesPlus and StrokesPlus.Net for a more than a decade. It works like a dream recognising those. Is free. I cannot believe a paid application, an app so feature rich as BTT — would be missing this simple a feature this late in its development.
Again, I cannot support the request for better simple gestures recognition enough.
Please, do tell me that something is in the works in this department.
Thanks so much.
Hello, Andreas. Could you please tell if there is any progress with this? Can we expect gesture recognition to become better any time soon?
Thanks so much!
