I write very complex reports with many, many objects. For the past two years using Telerik Reporting (which I love, don't get me wrong), I have been driven mad by the tree jumping to the top when I am working on a section towards the bottom.

Every tree view I have ever worked with has had an EnsureVisible on the selected node of the tree. Could you please find it in your heart to make this change. It takes me 20 times longer to build / modify reports than it has to.

I'm attaching my customer quote report so you can see the complexity I am working with and why scrolling back to where I was EVERY TIME is so maddening.

I've seen some suggestions similar to this, but none that are exactly the same.  I would like to have the ability to select any item within the Report Explorer and drag/drop it to the location that I want it to appear.  Perhaps this isn't possible due the way the Report Explorer works, but this would allow greater flexibility in where a control is located, versus the current Bring To Front/Bring To Back options.

Our client is strongly requesting a "zoom" by graphical selection feature, as available in their former tool qlikview (or amcharts,  for example).
I am surprised this feature has not been requested yet, since any user would greatly benefit from it.
It's an extremely powerful and intuitive way of restricting your selection of report input parameters in a visual manner. 
By drawing a rectangular selection with mouse over the graph, you restrict the range of both x and y axis to the selected ranges, allowing quick zoom to the area of interest
Examples: just draw selection rectangles on a chart in one of the examples below
https://www.amcharts.com/demos/scatter-chart/

http://us-b.demo.qlik.com/QvAJAXZfc/opendoc.htm?document=qvdocs%2FSocial%20Media%20Buzz.qvw&host=demo11&anonymous=true

After upgrading Telerik reporting to 10.2.16.914, I get the following error when trying to generate reports. The App.config hasn't needed any custimizations before. Why is it that every Telerik update always breaks our applications??? 

An error has occurred while processing Report 'OACLJB005':
The assembly "JobBank.Data, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" is not permitted to be used by an ObjectDataSource 
component. Please include it in an AssemblyReferences element in the Telerik.Reporting configuration section of your application configuration file.

I find it extremely limiting and frustrating to not have control over how the .NET Report class is initialized, and not being able to pass in any type of object/dependency (either into the constructor or by setting a property.) This makes it very difficult to keep custom reports decoupled from other code modules and make them unit-testable. 

There is the InstanceReportSource, which would have been perfect to solve this problem, but it's apparently deprecated.
http://docs.telerik.com/reporting/t-telerik-reporting-instancereportsource

DevExpress reports for example allow you to create the report instance yourself, and you can pass any objects you want directly into the constructor. 

This is what I find to be the biggest drawback to Telerik reports. 

just the same like here
https://www.combit.net/en/reporting-tool/pdf-object/

Support for Apple Numbers to be able to open reports exported in the "Excel Worksheet" format.

Would it be possible to prioritize which characters can "Break" when wrapping text inside a text box?  For example "foobar/foobar" will not break at the slash, it'll instead break at the character that hits the width limit. It would be my suggestion that punctuation be prioritized for "breaking" before all other characters, in the event that there is no space.

In the attached example, the column headers are dynamic (localized), and there's no way to predict what the text will look like (in whatever language)... Though I accept that no matter what, a string longer than the textbox width will need to break somewhere, I'd prefer that you break on "better" characters if they are present.

(Pretty nitpicky, I know, but this would save me trying to code the logic into an expression or function... which could prove complicated due to variable width of fonts)

We redefining an existing table style (ie. Aspect) in an external style sheet, the user should be able to select the style like now, but disable the style generation in the report file.
Currently, we need to go in the designer.cs file to remove all unwanted styles.

Currently, the designer automatically increase the width of parent containers when a control is moved or resize and goes outside the current parent size.

But this can be problematic with bad paging in some cases. 
As the automatic grow may be needed, I propose to increase the parent size with a settable minimal step:

When having set everything to have a width of 160 mm, just moving some controls can currently increase slightly the size (like 160.23 mm). But if the report has a minimal grow step of say 5 mm, in this case it will be resized to 165 mm, a visible size difference (therefore, layout can be corrected when the grow was unwanted).

In the Configure Object Data Source Wizard, add a method of filtering the displayed Business Objects.
Where a large number of Business are display, scrolling can be painful to find the required one.

As of the latest Reporting release the JavaScript size to download went from 61K to over 2MB. Our users work for charities and often have slow network connections. This is not an acceptable change for us.

Add the ability to control the relative position of text in relation to the image for both Radio & Check Boxes, such as TextImageRelation property used on your WinForms Radio & Check Boxes.
This would allow the following options: Overlay, ImageAboveText, TextAboveImage, ImageBeforeText, & TextBeforeImage.

On opening the Expression Editor, if at least one Data Source is present on the Report, then the Fields item in the tree should automatically be selected. If no Data Sources are present on the Report, then the default selection should be the Report Parameters.

The ability to use static values and display members as an array for a multi value parameter. I want my team to be able to use the standalone report designer without a custom User Function or a data source. We had been using SSRS and made a switch to Telerik, and this seems to be the only hangup that we are unable to convert cleanly.

Allow custom buttons and other controls to be added to the existing ReportViewer Control Toolbar.

The Standalone Designer allows a template to be loaded from a .NET dll. Add the ability to load a template from a .NET exe.

The report Parameter as of now can only be Boolean, Date, Int, Float or String. It would be great to be able to have a Guid parameter. This is particularly useful when passing a Guid to a child report parameter that in turns needs to be a Guid again to be run in the query. As of today we must convert the Master Guid to String to be able to assign it to a parameter then the child report reconverts it into a Guid to be passed to the query