Is it a good idea to give exit/close icon to top along with close button text after the content ends on a modal  If answer is not a good idea, please explain
I am working with a basic  which is a popular modal used on many sites. I noticed that the default template comes with both a close button on the bottom, as well as an x on the top, these two buttons essentially having the same purpose. Are the two redundant and the close button completely unnecessary and just taking up extra space? Or, is having multiple usage options more user friendly?   To make this even more fun, suppose I throw in a Save button:   Is it now clearer that if you don't press save and just press the x, your changes will be canceled, or is there now more of a need for a cancel button for users who are scared that a mistake will become permanent? Update: To clarify for those who feel this question is similar to  - That question is asking if a clickable background is sufficient to close a popup. I'm using buttons and it is just a matter of how many buttons to use. (I do also have a clickable overlay and ESC key enabled, but that is irrelevant to my question)
How to know if something is a primitive concept, a law, a definition or a theorem Some basic Physics books are often misguiding in the sense that they don't make clear whether something is a primitive concept, a law, a definition or a theorem. This is often a little confusing. I've asked here some moments ago if there's a definition of force, and I've been redirected to a question about whether Newton's Laws are laws or definitions of mass and force.  This is just an example, but there are many others, like for instance, the conservation of energy, which some books present as a theorem, and some places says that this is a law of Physics. Time on the other hand, is something that according to Feynman's lectures on Physics, cannot be defined, so we just say how to measure it and leave it as a primitive concept.  In this context: how in general can we identify whether something is a primitive concept, a fundamental law of Physics, a definition or a theorem? Requires installation of untrusted packages? I tried installing VLC Player yesterday, and I got the Requires installation of untrusted packages error.  I searched for hours for a solution to this problem, and finally came upon a suggestion that said to change servers for downloading updates from.  I did this, and it gave me a 404 error when I clicked on "Check" in the Update Manager.  I tried switching my server back to the main one (and after that, several other ones), but I am now still getting a 404 error:   And the other error I get when downloading or updating:   Edit: Output of cat /etc/apt/sources.list:  deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted #Added by software-properties  # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise multiverse universe #Added by software-properties  ## Major bug fix updates produced after the final release of the ## distribution. deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates restricted main multiverse universe #Added by software-properties  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ precise universe deb http://us.archive.ubuntu.com/ubuntu/ precise-updates universe  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu  ## team, and may not be under a free licence. Please satisfy yourself as to  ## your rights to use the software. Also, please note that software in  ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team.  ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse #Added by software-properties  deb http://us.archive.ubuntu.com/ubuntu/ precise-security main restricted multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise-security restricted main multiverse universe #Added by software-properties deb http://us.archive.ubuntu.com/ubuntu/ precise-security universe  ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. deb http://archive.canonical.com/ubuntu precise partner deb-src http://archive.canonical.com/ubuntu precise partner  ## This software is not part of Ubuntu, but is offered by third-party ## developers who want to ship their latest software. I have white blank on the posts.    App Version: 1.0.89 Device Manufacturer: Meizu Device Model: m2   OS Version: 5.1 (1464689330)    I can't see the questions and the answers and the comments.  I saw that it's a common issue..  Does it have a fix?   EDIT -  I saw  answer. This answer is ~2 years old. It says that it will fix in the next update.  His version is 1.0.59 - mine is 1.0.89. Huge different.   The problem is still exists! Find all functions $f$ such that $f:\mathbb{N}\rightarrow\  \mathbb{N}$ and $f(f(n))+f(n+1)=n+2$   Let us plug in $n=1$  $f(f(1))+f(2)=3$  Since the function is from $\mathbb{N}$ to $\mathbb{N}$, $f(2)$ can only take the values $1,2$. Now we divide the problem into cases.  Case-1: $f(f(1))=2,f(2)=1$  We can assume that $f(1)=c$ for the time being. Then plugging in $n=3$ and using $f(2)=1$ gives $$f(3)=4-c$$ and again since the range of the function is positive integers,then $4-c$ has to be positive and hence $c$ belongs to  {$1,2,3$}. Now, $$f(1)=c$$$$\implies f(f(1))=f(c)$$$$\implies 2=f(c)$$ by the assumption that $f(f(1))=2$ . Now,since $c$ can only take the values $1,2,3$,we start treating cases. If $c=1$,$$f(c)=2$$$$\implies f(1)=2$$ but we know from the deinition of $c$ that $f(1)=c=1$,a contradiction.If $c=2$,then $2=f(c)=f(2)$ but $f(2)=1$ by assumption. Finally,if $c=3$ $$2=f(c)=f(3)$$ but $$f(3)=4-c=4-3=1$$ which is once again a contradiction. Therefore there are no such functions in this case.  Case-2: $f(f(1))=1,f(2)=2$  Again assuming $f(1)=c$ and using $f(n)\le n$ along with plugging $n=c-1$ will give us that $f(1)=1$ and then it is easy to prove that such a function exists by recursion. I can only give a "sort of recursive" way to define the function. Here it goes $$f:\mathbb{N}\rightarrow \mathbb{N}$$$$f(1)=1$$$$f(n)=n+1-f(f(n-1))$$  But this case is harder to deal with.Some help will be appreciated. Finite order endomorphisms Why the finite order endomorphisms are diagonalizable over the complex numbers (or any algebraically closed field where the characteristic of the field does not divide the order of the endomorphism) with roots of unity on the diagonal? I am getting several new computers for my office.  I want to install Microsoft Office and my proprietary software and all updates on a single PC and create a system image that will be copied to every other PC.  How do I deal with Windows/Office product keys to prevent licence violations?  Am I able to do this from the System Image tool in Windows 7?  Note:  The PCs will very likely not be joined to my domain at this point if that makes a difference. How to correctly specify coordinate system? Using QGIS v. 1.9 (1.7 does not seem to be available for Ubuntu Linux 12.04), do the following:   Create new project, specify coordinate system by clicking on button in bottom right hand corner, enable on the fly CRS transformation, set projection to WGS 84 / UTM Zone 18S. Pass mouse over project window and UTM coordinates appear in coordinates window in status bar at the bottom. Add delimited text layer in decimal degrees. When asked for projection, specify same projection as in (1). Points in the layer are plotted but, mousing over the map, the coordinates in the coordinates window are now in decimal degrees (even though the projection is set to UTM).   Is there something I am missing here? I have tried doing this in so many ways, so many times, but the result is always the same. I seem to be setting the projection correctly but only decimal degrees show in the coordinates window.  With thanks, Martin Notify us when one of our posts is edited Your summary page shows "N Edits to your posts" for the selected time period but you really have to be looking for it.  Could we add edits to the notification feed? You could put the reason for the edit (entered--or not--when the editor changes it) and just a link to the post. On really old Ubuntu 6.06 - How to upgrade I'm on an old Ubuntu version (Ubuntu 6.06.2 LTS Server) which isn't really supported any more. So the automatic updates don't work. I have ISPConfig installed to manage a few web sites.  What's the best course of action? I'd like to upgrade to something current, but I can't figure out how to go about doing this, given that the apt-get scripts don't really work any longer. As you can see, objects are falling down when I run the game. Ground is unable to stop those obstacles. Obstacles are rapidly traveling through y axis. I tried by freezing y axis. And, unchecked Use Gravity. I tried by checking Is Kinematic also. But, if I freeze y axis. Than, obstacles completely freeze through y. If there was no ground than the objects don't fall. Same thing happen when I unchecked Use Gravity. I want those obstacles to move if Player hit them. How to stop those obstacles from falling down?   Info : How can I print the table of contents multiple times in my document? Compare 2 files and remove any lines in file2 when they match values found in file1 Story where radically different cultures live together and are defined by rulesets, some choose not to see each other, a house is used as a spaceship I think this novel came out in the 2000s.  There are many cultures that live close together but are very different, for example some pretend to be pre-industrial.  One of the main characters is a youth who grew up in a pretend pre-industrial society and is now exploring the rest of the solar system? ring-world?   Each culture experiences their own reality that is defined by a ruleset.  One of the rulesets becomes aggressively self-propagating and this is the problem that drives the plot.  At some point a tumbling house, just a normal house, is used to travel across space. Can I install the 64 bit version? How do we get Community Promotion Ads on beta sites? All the launched sites get Community Promotion Ads meta posts posted every year by a SE mod.  Previously, I thought that beta sites simply weren't allowed them. However,  is still in beta, and they had community promotions meta posts in  and  (I guess they haven't made one for 2015 yet).  So what happens? Do you just have to ask for one? Can the moderators of that site just create one as they like? Can anyone on that site just create one as they like? How to change the base of logarithmic-scale plots? What is the pressure at the center of the Earth? (Or a neutron star) The  has microgravity and is thought to be solid and almost 6000 degrees hot. What is the pressure like there? The confusing thing, for the common man I suppose, is that there's no gravity there, but lots of matter around it which does gravitate towards the center. How does that add up? Is the center just a gas cloud or is it highly compressed?  And I could add the aside question about what it is like in the microgravity center of a  or a black hole, but I don't expect anyone to know about that. Can you help me with my software licensing issue? When should the "Not an Answer" flag be used? No Indian (and Bengali) keyboard layout in Ubuntu 17.04? I've upgraded from Ubuntu 16.10 to 17.04 today. I'm from Bangladesh, and Bengali is my native language. There was an option to set keyboard layout to Bengali in all previous Ubuntu versions I've used. But there's no such option in 17.04, strangely. I can use Bengali by installing the package ibus-m17n,  so I thought maybe there was some problem during my upgrade. But then I checked my friend's PC which runs ubuntu 16.10 and found that ibus-m17n was not installed in 16.10 but there's option for Bengali keyboard layout. So is Bengali keyboard support really removed from 17.04, or was there a problem during my upgrade?