 Evaluating an integral using residue theorem
 Calculating curvature and offsets of curve segment
 Show that τ is a stopping time with respect to FX
 Show $\lim_{x \to x_0^+} f(x)(xx_0) =0$ when $f(\mathbb{R}) \subset \mathbb{R}^+$ & monotone increasing.
 Why is my proof that $L^1(\nu) = L^1(\nu)$ for signed measure $\nu$ incorrect?
 Why do finite restrictions of members of back and forth system are also back and forth systems and not just any restriction?
 Random walk with incommensurate steps
 Eigenvalues of $A+v_1d^T$ where $Av_1 = \lambda_1 v_1$ (shift of first eigenvalue)
 How can I pick up many distinct points at many line segments?
 Determine measure unit.
 Suppose H⩽G, prove that if (H,G′)=⟨e⟩, then (H′,G)=⟨e⟩.
 Problem 2. A comprehensive course in Analysis. Barry simon. Page 239.
 Exponent of a finite group $G$
 Does this prove the validity of this First Order Logic formula?
 Any countable set of real numbers is set of discontinuities of some monotone function.
 Prove order of a group is even
 substitution on multiple integrals
 When is the product of two nonsquare matrices invertible?
 Induced Semigroup Structures via (left) Translation
 Balls in bins prove that the probability that there is some bins of $k+1$ or more balls is at most $n/k^2$
Opensource text editor written in Qt
Is there a good text editor that is written in Qt? For example, for Gtk there is gEdit, Geany, and probably others. But I don't know any such editor written in Qt.
Please note, though, that I'm not asking about demo programs that took 2 days to write, that's not an equivalent to Notepad++ or gEdit.
Also, no KDE apps, I know KDE is based on Qt, but I'm interested in pure Qt applications. Otherwise Kate would be a candidate, it's a solid texteditor.
I want to be able to tweak the source code, so the source must be available.
what difference does it make? it's just a text editor, most of them are few MB big, I don't expect QT apps to be more lightweight than the apps out there, that being said, and since most Linux distro have GTK in them, I don't understand why a QT notepad would even matter.
I understand some users not wanting to install KDE apps on gnome desktop because it will install many dependencies. But wanting QT apps just because they are QT apps, I don

what difference does it make? it's just a text editor, most of them are few MB big, I don't expect QT apps to be more lightweight than the apps out there, that being said, and since most Linux distro have GTK in them, I don't understand why a QT notepad would even matter.
I understand some users not wanting to install KDE apps on gnome desktop because it will install many dependencies. But wanting QT apps just because they are QT apps, I don't understand that, certainly not to something as simple as notepad.
Having said that, take a look at TEA editor, they say that they offer two versions, a GTK version and a QT version, I quote
TEA is a text editor that provides a wide range of textprocessing
functions (over 100) and the syntax highlighting. There are two
branches of TEA: Qtbased and GTKbased.
That's all I know about it, you can find more on the about page. I never tried it and not interested in doing so. However the project seems inactive, their last release was i
20181019 14:54:55 
TEA is what you are looking for. It is a pure Qt, nonKDE text editor that runs on Linux and Windows.
I do not think that TEA is still in development, but compiled code should still run on newer systems and the code should still compile against newer software versions.
20181019 15:34:30 
I can not resist suggesting qvim, which is fullfledged gvim ported to Qt.
It is, of course, not a demo program that took two days to write; and it is accompanied by a pool of addons accumulated over twenty years... it goes far beyond Notepad++ or gEdit.
20181019 16:08:35 
Kwrite and Kate are my favorites.
TEA has a rather bad interface, Featherpad an odd behaviour when pasting a file path: opens the file in the text editor (maybe that can be changed, but I haven't used it anymore.)
20181019 16:10:44