Excel-DNA Custom Task Pane - Reduce Right-Side Host Strip to 2 Pixels

Hi, I am looking for a C# / Excel-DNA / Win32 developer to fix a layout issue in a custom Excel task pane. ***** This needs to work on Excel 2019 + ***** ## Problem The project uses an Excel-DNA custom task pane containing a custom-drawn text area and vertical scrollbar. The pane is bottom-docked and spans the width of Excel. At the far right side, Excel's task-pane host adds a grey strip between the custom scrollbar and the application window edge. This host strip is wider than the equivalent gap beside Excel's native vertical scrollbar. My guess is that you would manipulate the MsoCommandbar in some way and then fit the child back inside it. The target appearance is: * custom scrollbar positioned at the far right of the pane; * exactly 2 physical pixels between the scrollbar and the Excel application edge; * no additional white gap inside the custom control; * no duplicate grey strip; * no change to the existing 3 px separator on the left side of the scrollbar; * no change to the scrollbar width, appearance, or behaviour. *** Please see the attached images (Problem.png and Solution.png) *** Adding internal padding to the WinForms control is not an acceptable solution. That creates a white gap before the existing grey host strip and moves the scrollbar too far left. The actual task is to identify and reduce the width of the Excel/Office custom-task-pane host strip itself, or otherwise resize/reposition the relevant host window so the visible outer gap is exactly 2 pixels. ## Acceptance criteria The work is complete when: * the visible gap between the custom scrollbar and Excel's right application edge is exactly 2 pixels; * the gap matches the appearance of Excel's native vertical scrollbar; * there is no white strip before the grey outer edge; * the scrollbar remains 15 px wide; * the existing 3 px left separator remains unchanged; * the pane still works normally; * there are no crashes, flicker, resizing loops, or window-position errors; * the change works consistently at normal Windows display scaling and preferably across common DPI settings. My guess is that you would have to manipulate the MsoCommandbar and intercept what Office is doing to it. I currently use Excel 7 (2019) and it would need to work on that, plus later versions. If you can accomplish it on a later version, I would be happy to test it on Excel 2019. ## Deliverables * Updated C# source code. * Any Win32 declarations or helper classes required. * Buildable project files. * Before-and-after screenshots showing the measured right-side gap. In your proposal, briefly explain how you would identify the host window responsible for the grey strip. Generic C# or Excel VBA proposals are unlikely to be suitable.