What I want to do is click with the mouse and draw a rectangle on the map, around one or more markers, to select all the markers in the rectangle.  I've seen this done on other map controls by being able to select what happens when the user clicks on the map and moves the mouse. 

User selects "Pan" (usually from a tool bar)  - this is the standard behavior now
click on the map and move the mouse - map pans / moves with the mouse

User selects "Rectangle"  
click on the map, hold down the left mouse button, move the mouse and a rectangle draws - just like the windows "Snipping tool"  - all the markers in the rectangle get returned to the code in a collection when the user releases the left mouse button

User selects "Circle"  
click on the map, hold down the left mouse button, and move the mouse - a circle draws - all the markers in the circle get returned to the code in a collection when the user releases the left mouse button

Here's an example 
The shape file that's been converted shows all the telephone poles in a city.  I want someone to inspect all the poles on this street.  I select the rectangle tool, draw a rectangle around the poles, release the mouse, my code takes over and builds a work order to go inspect and record the inspection date and outcomes. 

Another example 
Map shows hotels in an area.  I select the circle tool, draw a circle around the hotels close to where my meetings are, release the mouse button, map returns a collection of markers in the circle, the program then takes over and displays a grid showing 
Hotel Name,   Star Rating, Average Rate, Phone number, URL