Convert `ArrayList` usage to `List<T>` where possible

[elachlan]

Is your feature request related to a problem? Please describe

Winforms uses Arraylist extensively.

Describe the solution you'd like and alternatives you've considered

Convert Arraylist usage to List<T> to reduce boxing and improve memory utilization.

Will this feature affect UI controls?

N/A

Related: #2644

Remaining occurrences in System.Windows.Forms.Design

File	Line Count
src\System\ComponentModel\Design\ExceptionCollection.cs	33
src\System\Windows\Forms\Design\ToolStripItemDataObject.cs	34
src\System\Windows\Forms\Design\ControlDesigner.DesignerControlCollectionCodeDomSerializer.cs	38
src\System\Windows\Forms\Design\UpDownBaseDesigner.cs	63
src\System\Windows\Forms\Design\DesignBindingValueUIHandler.cs	66
src\System\Windows\Forms\Design\ImageListImageEditor.cs	108
src\System\Windows\Forms\Design\ImageCollectionEditor.cs	113
src\System\Windows\Forms\Design\GroupBoxDesigner.cs	124
src\System\Windows\Forms\Design\ComboBoxDesigner.cs	128
src\System\Windows\Forms\Design\LabelDesigner.cs	146
src\System\Windows\Forms\Design\TextBoxBaseDesigner.cs	148
src\System\Windows\Forms\Design\OleDragDropHandler.CfCodeToolboxItem.cs	162
src\System\Windows\Forms\Design\ButtonBaseDesigner.cs	218
src\System\Windows\Forms\Design\Behavior\ContainerSelectorBehavior.cs	230
src\System\Windows\Forms\Design\ToolStripAdornerWindowService.cs	256
src\System\Windows\Forms\Design\BaseContextMenuStrip.cs	290
src\System\Windows\Forms\Design\OleDragDropHandler.ComponentDataObject.cs	302
src\System\ComponentModel\Design\InheritedPropertyDescriptor.cs	308
src\System\Windows\Forms\Design\Behavior\ToolboxItemSnapLineBehavior.cs	338
src\System\ComponentModel\Design\CollectionEditor.cs	347
src\System\Windows\Forms\Design\FormDocumentDesigner.cs	432
src\System\ComponentModel\Design\SelectionService.cs	446
src\System\Windows\Forms\Design\Behavior\SelectionManager.cs	458
src\System\ComponentModel\Design\DesignSurface.cs	491
src\System\Windows\Forms\Design\DesignerFrame.cs	576
src\System\Windows\Forms\Design\ToolStripDesignerUtils.cs	584
src\System\ComponentModel\Design\Serialization\CollectionCodeDomSerializer.cs	648
src\System\Windows\Forms\Design\DesignerUtils.cs	816
src\System\Windows\Forms\Design\Behavior\ResizeBehavior.cs	819
src\System\ComponentModel\Design\Serialization\BasicDesignerLoader.cs	857
src\System\ComponentModel\Design\Serialization\DesignerSerializationManager.cs	896
src\System\Windows\Forms\Design\ToolStripItemBehavior.cs	905
src\System\Windows\Forms\Design\Behavior\DropSourceBehavior.cs	1029
src\System\Windows\Forms\Design\OleDragDropHandler.cs	1045
src\System\Windows\Forms\Design\ToolStripItemDesigner.cs	1177
src\System\ComponentModel\Design\CollectionEditor.CollectionEditorCollectionForm.cs	1223
src\System\ComponentModel\Design\Serialization\CodeDomComponentSerializationService.cs	1471
src\System\ComponentModel\Design\DesignerHost.cs	1615
src\System\Windows\Forms\Design\ToolStripKeyboardHandlingService.cs	1891
src\System\Windows\Forms\Design\ControlDesigner.cs	2205
src\System\Windows\Forms\Design\ToolStripDesigner.cs	2260
src\System\Windows\Forms\Design\ParentControlDesigner.cs	2378
src\System\Windows\Forms\Design\ToolStripMenuItemDesigner.cs	2527
src\System\ComponentModel\Design\Serialization\CodeDomSerializerBase.cs	3020

This issue is now marked as "help wanted", and we’re looking for a community volunteer to work on this issue. If we receive no interest in 180 days, we will close the issue. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

[merriemcgaw]

This is a great idea, and a wonderful place for the community to engage and find the right areas to make changes like this. Of course, we'd need to avoid making this happen on the public surface area 😄

[elachlan]

One issue I have run into is that there are a few collections which expose IList.IsFixedSize, List<T> doesn't have that property. I don't think FixedSize() gets called either. So it might be an idea to change IsFixedSize to just return false?