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C# WinForms Panel Child Positioning Being Very Wonky?

Here is the problem. If you dynamically place controls in a panel, it works fine, but only until the vertical scrollbar appears. Once there is enough content for this to happen, it starts positioning controls nonsensically.
In my window, you can click a button to add another row of controls inside the panel, which represent options for an item in a list. If you scroll the vertical scrollbar on the panel all the way down and click the button again, the new row of controls will be positioned below the bottom edge of the panel out of view. If you scroll down, there is a huge gap between the new row and the previous row of controls. This should not happen. The positioning code is working flawlessly, as proven by debug output. As far as I can tell, the problem is the stupid anchoring system, however disabling anchoring on these controls does not fix the problem as one might expect. Instead, it just makes it position them wrong in a different manner. This makes no sense at all, and is super annoying!
I tried disabling Autoscroll in code before controls are added to the panel. No change. So I modified that code to disable both the vertical scroll bar and Autoscroll and set the scrollbar to not visible before controls are added. No change again, except that the now disabled vertical scrollbar still manages to appear usable when there is enough content in the panel in spite of it being disabled and set not visible!? That's not supposed to happen when I disabled and made it invisible! With anchoring disabled on the controls being added to the panel and once the vertical scrollbar has appeared, clicking the button to add a few more rows of controls now causes them to be indented a bit for no reason and positioned overlapping each other a bit vertically! It's as if the coordinate system in the panel has somehow arbitrarily changed, because of the presence of a vertical scrollbar and anchoring being disabled on the controls? The debug code shows that the controls are all being placed at correct coordinates, yet they appear positioned very wrongly. So my code is working perfectly, and therefore something else is the problem here.
Everything behaves exactly as expected up until the vertical scrollbar appears. This is so bizarre. Does anyone have any idea what on earth is going on with this stuff? Apparently it is far easier to make it do stupid stuff than to get it working properly.

Thanks again! I got it working. I went with TaW's solution first since it seemed like the simplest solution. Incidentally, I already tried TaW's approach days ago when I was fighting with it, but I had naturally subtracted the AutoScrollPosition value rather than add it, because I didn't expect it to be a negative value!
It seems very odd that control positioning is relative to the current AutoScrollPosition, as absolute coordinates seems like a much more natural, intuitive approach than having negative numbers. I guess that would make it slightly harder to place a control in the currently visible area, but I suppose that's not a big deal as most scrollable interfaces are probably initialized ahead of time and don't need to do that anyway.

Implementing scrollable table on Windows Phone

I need to create an app for TV guide. Requirement is that UI must be a copy of one you can see here: raspored.bnet.hr. As you can see, there's a lot of data. So, basically it would be a large scrollable table. Since there is no such UI control as table on Windows Phone, I found out that the best approach would be to create one vertical listbox with horizontal listboxes as its items. This is all ok and I'm able to create it. But, to make it behave like a table I also need to make these horizontal listboxes scroll in sync, not to scroll one row at a time. Then I disabled horizontal scroll on horizontal listboxes, and enabled it on the parent (vertical) listbox and while it gave the result I wanted to achieve one big problem came up - UI virtualization. I know ListBox has UI virtualization enabled by default and I can see it while scrolling on vertical listbox, but when I disable horizontal scroll on horizontal listboxes, performance is really bad, and sometimes there's an OutOfMemoryException. I understand why this happens because when I disabled horizontal scroll, those listboxes didn't know which items are on screen anymore, so the loaded all of them into memory.
What I also tried is to leave scroll on every listbox so they have UI virtualization, and then place ScrollViewer above them. Then I tried to listen on Manipulation events on scrollviewer and progamatically scroll all of the listboxes as needed. This didn't work good, first of all ManipulationDelta event doesn't appear to fire frequently enough to make scrolling smooth, and I think there could be a performance problem with calling ScrollToHorizontalOffset on ~180 listboxes.
I also tried the LongListSelector from WP8 as I read that it has much better UI virtualization and should be used instead of ListBox. The problem with this is that I couldn't make it scroll horizontally. Is it possible at all? I tried to wrap it into ScrollViewer which can scroll horizontally and it's working, but only if I set fixed width on LLS.
I also tried Telerik's RadDataBoundListBox and the problem was similar, I can't get both horizontal and vertical scrolls on the same listbox. So I could only get that each list scrolls on its own.
Can someone tell me if they had similar situation and what would be the best approach to solve this? I believe I'm not the only one that has this requirement to implement large scrollable table.
Thanks
UPDATE:
I'll just inform you that I didn't find a proper way to implement this, instead I've done it in HTML with WebBrowser control. Seems like IE already has UI virtualization implemented so it can work with large pages very well.

May be in your listbox there are images? and Out of memory Execption will occur you can do 2 things:
Don't load data in one time use BackgroundWorker
Have one local image in the App of the image you are downloading and set it as default image & when you scroll to some 50 values in forward clean the image Url to local and when it comes back give again the image url you want to show .
Because i have used it to scroll around 20k values.

WPF expander troubles

I used many expander in the WPF application.. but I face some troubles:
When I try to put them below each others, the upper one expands automatically and makes it difficult to put the net one below it.. So I should separate the upper one in any place until I put the lower one then move back the upper one again. Can I keep expander unexpanded to make it easy to put any controls below it?
When I press ctrl+f5 and expand one of them, I see it has a transparent background and makes interruption with the lower ones - how can I avoid that?
I used scroll bar inside expander, but it doesn't work when i press ctrl+f5. I have an inactive scroll bar. How can I make link between scroll bar and expander to be able to move items inside expander up and down?
This is a picture to explain what I mean.

have a look at ths tutorial, it covers stuff like this, The Expander can be a tricky control to deal with sometimes, but once you understand the the expanders layout it becomes a bit easier.
http://blogs.msdn.com/b/wpfsldesigner/archive/2010/02/03/taming-the-wpf-expander-control.aspx

WPF snapping controls

my current free-time project, in order to dive into WPF MVVM, is a "digital" copy of an old puzzle I used to play a lot in my childhood. It basically is a simple puzzle where one has to fill a given space with different kind of pieces so the whole space is filled. But with the extra twist of being in hexagonal space.
Just to illustrate, this is what it currently looks like in WPF:
http://img190.imageshack.us/img190/2553/atomgridmolecule.png
So basically there is a number of predefined pieces(like the orange one above) which can be "plugged" into the given grid(the gray stuff above).
So the result might look something like this:
http://img30.imageshack.us/img30/2553/atomgridmolecule.png
I want the user(probably only me^^) to be able to drag and drop the pieces into the grid. I want the dragging to look natural meaning having the correct offset while dragging depending on where the user clicked the piece.
Both grid and molecule are the same control, a custom hexagonal panel control derived from the WPF Panel class.
The problem is on how to do the "plugging in" and especially the "unplugging".
I have two ideas on how I might tackle this:
Just color the cells in the grid and hiding the original piece
Pro:
Zero cost perfect alignment of the cells
Cons:
Recreating the piece at the right spot with the correct mouse offset if dragging out, seems impossibly? hard to do
Snapping the piece to the grid and show it on top
Pro:
Dragging out is a simple dragging operation, just as dragging in
Disadvantage:
Somehow have to align the piece with the underlying grid, some kind of snapping
So which approach should I take? Even more important how can I even implement this in WPF? Especially using a clean MVVM way.
Thanks so much for your help! Any input is highly appreciated!
EDIT:
Thanks Aran, I thought so too.
But how do I actually implement this now?
How can I actually get the coordinates?
All the orange circles are linked, so how can I "move" or better "plug" them in as one piece?

Im inclined to go with the second idea. a simple snapping would just be to test if the centre point of the circle you are dragging is within some tolerance factor of a circle on the grid and if so snap them.

C# Containers -- Filling a Space Vertically on Resize

I'm new to C# and I've been working on a small project to get the feel with Visual Studio 2008. I'm designing the GUI in C#, and I have a TabControl with three GroupBoxes. These three GroupBoxes are anchored to the left and right of the screen and work perfectly when resized horizontally.
I would like these three boxes to take up 33% of the height of the screen, and gracefully resize. I've tried messing around with anchoring, but I can't seem to find the answer. I've also been searching for something similar, but unfortunately, searching for positioning containers yields all CSS and HTML stuff.
This seems like a pretty common thing to do, but I can't seem to find an easy to way to do it. If someone could point me in the right direction, I'd greatly appreciate it.
Thanks!

Try out the TableLayoutPanel. I believe it does exactly what you want. It allows you to define columns and rows within its area, specifying their width (for columns) and height (for rows) in percentages or pixels. You can then drop a group box into each cell and set its Dock property to Fill, and it will nicely resize along with the cell when the TableLayoutPanel resizes (which can be easily achieved by using docking or anchoring).

This is really a shot in the dark but maybe you could try using split-panels ?
Edit: I've just checked in Visual Studio and I think the TableLayoutPanel might do what you want.
Edit2: dang, beaten to the punch :)

Handle the form's Resize event: Add code to compute the new size/position of the controls in there. Beware to interferences with the controls' Anchor property. You may have to Anchor to None and compute left and right position yourself as well.
Since you're learning, I guess you prefer not to receive a full solution but rather a direction. No code from me then ;-)