Could we perhaps change the touch buttons to glow or fill in solidly when touched, rather than growing to a huge size? I looked at a few other emulators on Android (Drastic, Retroarch), and they make the buttons glow or have a pressed down animation, rather than making their size grow huge.
Well, most state changes other than growing will not be visible on a touch screen as the finger you are touching them with will cover them. I just did the large size thing because it was easy and it works. A glow that reaches out some distance around it would work too and would probably look better.
Feel like making a mock-up picture of what you would like it to look like? If you make something I like enough I'll even implement it for you :)
How about a halo effect around the edge of the button that spreads out several pixels like you suggested, maybe like this (pardon the MS paint image, I'm not that great at image editing):

The glow wouldn't have to be red, of course, or so intense in shade.
The Color of the glow could be user definable anyway.
With a sliding scale showing all colors available.
Could call it in the menu, "Controls & Button Illumination settings."
Or if we don't want to have it be customisable, perhaps make the buttons glow the colours of the PS2/PS3 controller buttons? Might be neat. For the dpad/analog stick/start/select and L/R it could be something "generic" like white, or a gentle blue.
You can also add a slider to tweak the enlargement multiplier. There's a similar feature in ePSXe called "Button magnification on press".
The glow feature seems nice too.
Bumping any further improvements to 1.8.0.
Can you add like this color button style?

Because it's cool in the eye and my favorite color is blue 馃槑
I don't like the classic button even it is blue :/
Is this from one of those PPSSPP clones or did you make it yourself?!
Nonetheless I like it better than the classic buttons too!
We actually could color the borders whatever. I think that was the result of using an older PPSSPP version with the ini setting for border style set to glowing borders (because this causes it to use the standard thin borders, but with the blue color.)
-[Unknown]
@unknownbrackets yeah your right 馃憤
You can add CUSTOM buttons/skin unknowbrackets?
Not yet.
Why?
@iota97 can you make custom skin buttons for ppsspp like DraStic have?

This is one of the features ppsspp don't have but others emulators already have..
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Bumping any further improvements to 1.8.0.