another day another vice another roll of the dice: July 2007

Thursday, July 26, 2007

CSS two column float layout - 3px bug workaround

Take this typical two columns float layout. Left column holds menu, right column is for content. What's wrong with it? Nothing, unless the talk is about IE6. By CSS design there should not be any space between left menu column and content on the right, but in IE6 there is.


<html>
  <head>
    <title>Float Layout - 3px IE Bug</title>
    <style type="text/css">

html, body {
  margin:0px;
  padding:0px;
  border:0px;
}

#wrapper {
  margin:0px;
  padding:0px;
  border:0px;

  height:100%;

  background:#ffffff;
}

#left {
  float:left;
  width:175px;
  margin:0px;
  padding:0px;
  border:0px;
  background:#eedddd;
}

#right {
  height:100%;
  background:#bbeebb;
  border:0px;
  margin:0px;
  padding:0px;
  margin-left:175px;
}

p {
  margin-top: 0px;
}

    </style>
  </head>

  <body>
    <div id="wrapper">
      <div id="left">
        <p>menu</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
      </div>

      <div id="right">
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
      </div>
    </div>
  </body>
</html>

If IE5 is a history for now, IE6 is used by one third of Internet users. So, for CSS beginners, the quick fix to solve this IE problem with additional space around floats is to make this space eaten by negative margin of the float itself. In practice this looks like:


#left {
  float:left;
  width:175px;
  margin:0 -175px 0 0;
  padding:0px;
  border:0px;
  background:#eedddd;
}

See example files at: http://rainforce.org/pile/css/

Thursday, July 19, 2007

Firefox window top margin "bug?"

Sometimes Firefox may render additional margin at the top of the window even though all margins of top-level boxes and html/body container are set to zero. For example:


<html>
  <head>
    <title>FireFox Top Margin "Bug?"</title>
    <style type="text/css">

html, body {
  margin:  0px;
  padding: 0px;
  border:  0px;

  font-family:sans-serif, Tahoma, Arial, Helvetica;
  font-size: 10pt;
  background-color: #ffffff;
}

#maincontents {
  margin:  0px;
  padding: 0px;
  border:  0px;

  height:100%;

  background:#bbeebb;
}
    </style>
  </head>

  <body>
    <div id="maincontents">
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
        <p>filler</p>
    </div>
  </body>
</html>

The strange thing is that margin disappears if you set border and make it visible, i.e. add border:1px solid to #maincontents style.

While it looks like a bug this case is actually covered in specification. In particular it is said that adjoining margins are those of boxes not separated by padding or border areas. It is also said that these are collapsed to form a single margin for unlimited number of nested boxes. The margin height is equal to maximum margin from the set of boxes.

So if you do not want any margins like that - and top window margin is just the specific case of it - you may try to make troublesome box floated or teach children how to behave properly.


#maincontents {
  margin:  0px;
  padding: 0px;
  border:  0px;

  height:100%;

  background:#bbeebb;
}

#maincontents > :first-child {
  margin-top:0px;
}

See example files at: http://rainforce.org/pile/css/

Friday, July 06, 2007

How to recover windows registry keys from NTUSER.DAT

Have you ever experienced crashed windows? Crashed so badly so you have to reinstall it almost from scratch with simple file copy as the only mean for backup your precious files. Even if documents can be successfully retrieved by copying HDD contents from another (or even from the same) station, there is no way to get back precious customizations and passwords previously hidden in the depth of windows registry. Well, unless you haven't forgot to copy your NTUSER.DAT from within your profile located in "Documents and Settings".

There are two ways to get back missed registry keys. Manual and automated. Before starting with manual bot instruction of doing things let me introduce some concepts. NTUSER.DAT is a registry hive. Windows allows to temporary mount hives into subkey of HKLM or HKU root entries either manually with regedt32.exe tool or in batch mode with reg.exe (standard utility in WinXP and part of SUPPORT\TOOLS of Win2000 installation CD). Then hive is mounted it could be accessed by other tools, such as regedit.exe

The process of manual export of registry keys from backuped NTUSER.DAT:
1. start regedt32
2. select HKEY_LOCAL_MACHINE window and root key
3. Registry->Load Hive... specify your NTUSER.DAT
4. enter new key name to place registry tree under (I chose temphive)
5. now launch regedit and navigate to the same entry (i.e. HKEY_LOCAL_MACHINE\temphive)
6. Registry->Export Registry File... specify .reg file name
7. make sure temphive is not accessed by regedit.exe and switch back to regedt32.exe
8. make sure temphive is selected and issue Registry->Unload Hive...
That's all.

Automatic export with reg.exe is governed by the following ntuset.dat.export.bat:


reg.exe load HKLM\temphive NTUSER.DAT
regedit.exe /e regexport.reg HKEY_LOCAL_MACHINE\temphive
reg.exe unload HKLM\temphive

This .bat file creates regexport.reg file with contents of NTUSER.DAT from current directory.